Current time in Tokyo: July 25, 10:15 a.m.

After decades of trying to get into the Olympics, skateboarding makes its debut with the men’s street contest at sweltering, sun-baked Ariake Urban Sports Park. Twenty men qualified for the event, and by midday Sunday in Tokyo, the first skateboarding gold medal will be awarded.

We arrived 90 minutes before the first heat, and skaters were already warming up, quite literally. Temperatures were expected to be in the 90s, and shade is almost nonexistent. As with most skate contests, there is music and an upbeat announcer. There is no crowd, of course, other than a swarm of sweating reporters sitting on one end.

The most attention will fall to Nyjah Huston, the 26-year-old American widely regarded as the best contest street skater in history and the subject of a deep New York Times profile this week. He has won all the major events of skateboarding, including world championships, the Street League Skateboarding series, the X Games and the Dew Tour events. His home in Laguna Beach, Calif., has a trophy room that can barely contain all the trophies and medals. He is likely to squeeze in one more here at the Olympics.

His biggest challenger for gold is a local skater, the 22-year-old Yuto Horigome, the son of a Tokyo taxi driver (we wrote about that, too) and Huston’s biggest rival the past couple of years. In the first major post-pandemic events this spring, Huston won a Dew Tour contest, and Horigome then won the world championship in Rome. If there is an upset here, it will be that the two of them do not finish 1-2, in either order.

But the field is deep, and plenty of athletes arrived with realistic medal hopes. The Americans Jagger Eaton and Jake Ilardi are among them. With skateboarding’s four events at the Olympics (men’s and women’s street and men’s and women’s park), the safe bet is on one of three countries: the United States, Japan and Brazil. But there are outliers, and it would not be a surprise if, say, Vincent Milou of France skated to a medal today.

Here’s the format: The athletes were divided into four heats of five skaters. Each will perform two timed runs through the skate park, hustling through their own path over the rails, bumps and ledges. Falling does not disqualify anyone, but it will not help their scores.

The skateboarders will also get to attempt five tricks of their choosing. A panel of judges will score each run and trick — seven in all — on a 10-point scale. The best four scores are added together.

The skaters with the top eight scores will advance to the final. All of the preliminary scores are scrubbed, and the process repeats from scratch. Before these athletes go to lunch, someone will have won a gold medal.

The skateboarders have spent the past few days practicing at the park, an hour or two a day, trying to figure out which features to hit and string together. The response to the park is universal — it is big, fun and incredibly hot.

Two words: Simone Biles.

At about 2:10 a.m. Eastern time, the transcendent American star of the Games takes to the uneven bars, the beam, the vault and the floor for the first time at these Olympics. For American television viewers, NBC is showing the competition in its prime-time coverage, beginning at 7:30 p.m. Eastern on Sunday.

Swimming is always an anchor of the first week of the Games, and the first four golds are set to be awarded starting at 9:30 p.m. Saturday Eastern time, perfect for live prime-time viewing. On tap are the grueling 400-meter individual medleys. That’s a chance for an international star to shine: Katinka Hosszu of Hungary. The men’s 400 meter freestyle and the women’s 4x100 free round out the lineup.

Naomi Osaka will always be remembered for these Games after lighting the cauldron at the opening ceremony. She will also want to be remembered for winning the tennis gold medal; she opens against Zheng Saisai of China.

April Ross and Alix Klineman are the new American stars in women’s beach volleyball and will try to follow in the footsteps of the legendary team of Misty May-Treanor and Kerri Walsh Jennings.

After some stutters in exhibition games, the American men’s basketball team plays for real for the first time, and its opponent is a good one: France, which features five N.B.A. players, including Rudy Gobert.

Here are some highlights of U.S. broadcast coverage for Saturday evening, including the first appearance of skateboarding in the Olympics and the next game for the seemingly unstoppable U.S. softball team. All times are Eastern.

• Skateboarding: Men's street skateboarding makes its Olympic debut, with live coverage of the preliminary runs starting at 7:30 on USA. Coverage of the finals starts at 11, also on USA; NBC picks it up at midnight.

• Beach volleyball: Preliminary matches will be included in NBC’s multisport coverage starting at 8. At 9, NBCSN will rebroadcast an earlier match between Phil Dalhausser and Nick Lucena of the United States and Alexander Brouwer and Robert Meeuwsen of the Netherlands. NBC plans additional coverage during its overnight broadcast, starting at 2 a.m.

• Rowing: At 8, CNBC has repechages in men’s and women’s single sculls and pairs. At 11, CNBC has replays of heats in the men’s and women’s eights.

• Swimming: NBC will include the finals of the men’s and women’s 400-meter individual medleys in its multisport coverage starting at 8, with additional coverage during its overnight broadcast starting at 2 a.m.

• Three-on-three basketball: Look for live coverage of a preliminary game during NBC’s multisport coverage starting at 8. Additional coverage starts at 8 on CNBC and at 10:40 on USA.

• Softball: The U.S. women are on a roll, and they face Australia at 9 on CNBC, with a replay at midnight on NBCSN.

• Tennis: First-round singles and doubles matches continue, with coverage starting at 10 on the Olympic Channel.

• Volleyball: NBCSN has a replay of the men’s match between the United States and France at 10. The U.S. women take on Argentina in a Group B match at midnight on NBC.

• Archery: USA has elimination-round coverage at 10:40, and CNBC will carry the final of the women’s team event at 3 a.m.

• Cycling: Coverage of the women’s road race starts at midnight on USA.

• Table tennis: The mixed-doubles quarterfinals start at 12:20 a.m. on CNBC.

• Water polo: CNBC has the men’s Group A match between the United States and Japan at 1 a.m.

• Gymnastics: The men’s team competition is in the mix during NBC’s overnight coverage, starting at 2 a.m.

• Diving: The women’s synchronized springboard competition starts at 2:10 a.m. on CNBC.

• Fencing: Coverage of women’s individual foil starts at 3 a.m. on CNBC.

— Eric Morse

In a telephone interview about a week before leaving for the Tokyo Games, Simone Biles was asked to name the happiest moment of her career.

“Honestly, probably my time off,” she said.

Coming from the most decorated gymnast in history, a woman who revolutionized the sport, it was a striking comment.

Five years ago, Biles did everything her sport and her country asked her to. Sporting a red, white and blue bow in her hair, she helped the United States women’s gymnastics team secure its third consecutive team Olympic gold medal and then won three individual gold medals, in the all-around, the vault and the floor exercise. She emerged from those Games as America’s sweetheart, the itchy sash placed on every great American female gymnast.

Then, only weeks after she returned from Rio, came the revelation that the people responsible for protecting gymnasts and safeguarding the integrity of the sport had failed catastrophically to do either, revealing an entrenched culture of physical and emotional abuse.

U.S.A. Gymnastics had looked the other way as Lawrence G. Nassar, a longtime national team doctor, molested hundreds of female athletes, including many of Biles’s teammates — and, though it took time for her to realize it, Biles herself.

She has said she feels betrayed, and that makes the initial trauma even worse. Yet she has managed to set aside those feelings and harness the newfound power of an independent Black woman who knows her worth and answers to no one. No longer just a sweetheart, she has joined top Black female athletes like Naomi Osaka and Serena Williams in flexing her influence in sports and society.

In a show of defiance and resilience in a sport that has long demanded obedience from its young athletes, Biles is the only Nassar survivor, at least the only one who has come forward publicly, who will compete in Tokyo.

“I’m going to go out there and represent the U.S.A., represent World Champions Centre, and represent Black and brown girls over the world,” she said in the telephone interview. “At the end of the day, I’m not representing U.S.A. Gymnastics.”

This is the debut of skateboarding at the Olympics, but it will look a lot like other major skate contests, such as the Dew Tour or Street League Skateboarding.

There are two distinct disciplines: street and park, both of them judged by a panel, each with their own qualified athletes. If you watch snowboarding at the Winter Olympics, think of them a little like slopestyle and halfpipe — variations in the setting that feature slightly different types of acrobatics.

Men’s street skateboarding will be held on Sunday, July 25. Women’s street will be held the next day, on Monday, July 26.

Both street competitions are top-heavy with favorites. For the men, Nyjah Huston of the United States is considered the best street skater in the world. His biggest rival is Japan’s Yuto Horigome, who beat Huston at June’s world championships and might emerge as one of his country’s big Olympic stars.

The women’s street contest could see a Brazilian sweep. Impeding that possibility might be skaters from Japan and the United States, like Mariah Duran or Alana Smith. But Brazil has three of the world’s best: the five-time X Games gold medalist Leticia Bufoni, Pamela Rosa and Rayssa Leal, who is just 13.

Women’s park will be held near the end of the Olympics, on Wednesday, Aug. 4. Men’s park will follow the next day, on Thursday, Aug. 5.

Because of the time zone difference, these competitions will begin the previous evening on the East Coast and end after midnight. They will be shown on NBC, CNBC or the USA Network.

For better or worse, the Tokyo Olympics are finally here. And that means an extraordinary burden will fall again on the shoulders of a single group of athletes: Black women.

Simone Biles is one of the most brilliant talents at the Games. But if recent history holds and she tries her most stunning moves in Tokyo, gymnastics officials will place an arbitrary limit on her score. Some say this is meant to discourage other competitors from attempting similarly dangerous aerial maneuvers. I say the sport’s regulators cannot deal with her sheer audacity.

Naomi Osaka is a supernova, perhaps the most widely known female athlete on the planet not named Serena Williams, Osaka’s idol who astutely decided not to bother with the Games. But Osaka will get tossed under the bus if she is not polite and pleasant in her interviews with the news media, a backlash prompted by her withdrawal from the French Open because she did not want to participate in news conferences there. That pressure exists alongside the dread that she’ll be derided as either too Black or not Japanese enough if she does not win a gold medal.

Gwen Berry is one of the most powerful hammer throwers in the world and one of the boldest athletes in protesting racism and injustice. But the Olympic overlords have made clear she’d better behave on the medal stand — or else.

These Games will have a split personality. They will lay bare the Olympics’ greedy quest for billions of dollars in profits from sponsorships and television contracts that, in this case, have forced the event upon a Japanese public that wants them canceled amid a surge in coronavirus infections and state of emergency.

They will provide heart-stopping, dramatic performances, although no fans will be able to watch in person.

They will show something else. The structure that wraps around and organizes sports, particularly the Olympic movement, fails in supporting women — distinctly so for Black women.

The first day of women’s gymnastics is a marathon: The qualification rounds, which decide which teams and athletes will vie for medals, last about 12 hours.

For the Americans, the story to watch is which athletes, besides Simone Biles, will move on to the all-around competition and the event finals. Find out what you need to know, including how to watch, who’s who among the Americans, how the scoring works and how the team and individual qualifications work.

At least 35 members of the 583-strong Japanese Olympic team are multiracial. They are considered medal contenders in tennis and judo and will compete in boxing, sailing, sprinting, rugby and fencing, among other sports.

Their ranks include two of the highest-wattage athletes on Team Japan: Rui Hachimura, the basketball player whose mother is Japanese and father is Beninese, and Naomi Osaka, the tennis champion whose father is Haitian American and whose mother is Japanese. On Friday, Ms. Osaka, 23, climbed a flight of stairs etched into a pyramid shaped like Mount Fuji and lit the Olympic cauldron perched on top.

That two of the opening ceremony’s star roles went to multiracial athletes underscores how eager Japan is to present a diverse face to the world. Ms. Osaka’s and Mr. Hachimura’s popularity in Japan had already been confirmed when Nissin, the instant noodle manufacturer, affixed their faces to Cup Noodle packaging, an advertising honor akin to appearing on a cereal box.

But even as Japan celebrates the accomplishments of its “hafu” athletes — “half,” as in half-Japanese and half-something else — it must still contend with xenophobia in a society whose ideas of nationhood are tied to race.

“My entire existence has been a challenge to those around me of what it means to be Japanese,” said Sewon Okazawa, an Olympic welterweight boxer who is the son of a Japanese mother and a Ghanaian father.

Twenty-three sports kicked off play on Saturday in Tokyo, including table tennis, gymnastics and swimming. Here are some of the best photos from the New York Times team on the ground.

LAGUNA BEACH, Calif. — Nyjah Huston was driving his Mercedes coupe well past the speed limit between his $3 million house overlooking the Pacific Ocean and his private indoor skatepark where he was training for the Olympics.

He was talking about how he had gotten there and, now, about the distance between public perceptions and inner feelings.

It can be hard to be an adult when you weren’t allowed to be a child. To know who your friends are when you had none as a boy. To learn when you have never stepped inside a classroom. And to build trust when your deepest relationship shattered on the fragile edge between childhood and adulthood.

He idled at a stoplight.

“Nyjah!”

A little voice broke his concentration. Nyjah turned his head. There was a boy on the sidewalk, with a smile, a nod and an enthusiastic wave, as if seeing Santa in a passing parade.

“Hi, Nyjah!”

Nyjah smiled, nodded and hit the gas.

At 26, he belongs to the single-name realm of LeBron, Tiger and Serena. He is the second-most-famous skateboarder on the planet. (Tony Hawk, now 53, may never surrender the title.) He has been famous for three-quarters of his life.

But a new audience is about to experience Nyjah for the first time as skateboarding makes its Olympic debut in Tokyo, starting with the men’s street competition on Sunday.

The Olympics have never had an athlete like Nyjah or a story like his.

The U.S. swimmer Katie Ledecky’s domination is so routine that her surname has become a verb, synonymous with crushing the competition. For nearly a decade, she has ledeckied away in her specialties — distance swims longer than 400 meters — rarely facing a true challenger and certainly nothing resembling a rival.

Now she has one.

Ariarne Titmus of Australia, a fearless Tasmanian who talks big and has the speed in the pool to back it up, is about to ask Ledecky the one question she has never had to answer in her two previous Olympic appearances: How will she respond to a swimmer who has placed a target on her back and taken dead aim at it?

“I’m sure she is going to be fast, and I’m sure she thinks the same of me,” Ledecky, 24, said of Titmus in a pre-Olympic news conference this month.

How fast is Titmus? Lately, when it has counted most, she has been a good bit faster than Ledecky at both 200 and 400 meters, races that Ledecky swept four years ago.

At Australia’s Olympic trials last month, Titmus, 20, missed breaking Ledecky’s world record of 3:56.46 in the 400 by just half a second. At the U.S. trials, also in June, Ledecky swam the distance in 4:01.27.

In the 200, Titmus came within 0.11 of a second of the record, which was set in 2009, when swimmers wore sleek suits that reduced drag, which are now banned. Ledecky swam the 200 freestyle at the U.S. trials in 1:55.11, more than two seconds behind the world record.

Aside from her times, Titmus’s comments after the trials rocketed across the swimming world.

“She’s not going to have it all her own way,” Titmus said of Ledecky after her 400 race.