Blackjack is a game of stick or twist. Hit 21 and you have executed the perfect game plan, stick and you may have played it too safe. Twist and you could go bust.

It is a tricky balance to strike, not least when you are trailing 1-0 going into an away Champions League second leg semi-final in front of a raucous 72,262 fans at Barcelona’s Camp Nou.

There were concerns that Emma Hayes’ line up was too conservative. Barcelona know how to play against teams that drop off. You cannot help but think — why not just have a go? But that is a risky scenario, one which leaves you vulnerable to being ripped apart.

Barcelona have done that to other teams in ruthless fashion. Before this game, the 2022 Champions League finalists had won every game at Camp Nou and recorded frightening scorelines of 5-2, 5-1, 3-0, 6-0 and 5-1. That is 24 goals, an average of 4.8 per game. Although Chelsea’s 2-1 aggregate defeat saw them knocked out of the competition, the 1-1 draw was the first time Barcelona have failed to win a game at Camp Nou.

The whistles within Barcelona’s fortress were piercing. Whenever Chelsea had the ball, it was like a ticking time bomb, waiting for the opposition to lose possession. When they did, the hypnotic rhythmic drum beat and chanting restarted and comforted the home side.

It is no wonder Barcelona have won their last 18 home Champions League games — an unbeaten record spanning four years. Fully aware of the threat they posed, Hayes’ game plan was, in her words, “to survive in the first part of the game”, not concede and wait until later on in the second half to bring on a more attacking threat with fresh legs.

“If I’ve learnt anything from my career, you have to stay in football matches,” Hayes said after the 1-1 draw in the second leg. “Had they got a goal early on they would have given us a difficult evening.”

In the first half Chelsea did not have a single shot and created nothing (as demonstrated by the flat yellow line below) but equally Barcelona did not register an attempt on target, despite nine efforts. Barcelona have never gone in 0-0 at Camp Nou. From that perspective, Hayes was happy. Her game plan was working.

In the second half, Chelsea knew they needed to exert slightly more pressure without exposing themselves. But Barcelona’s goal came from a Chelsea overload. They could not catch player of the match Aitana Bonmati as she sprinted down the middle of the pitch before teeing up Caroline Graham-Hansen to finish in the 63rd minute. Barcelona scored on their first attempt on target.

Hayes had decided to stick but now Chelsea needed to twist.

And they did. Erin Cuthbert’s sliding challenge to dispossess Mariona Caldentey triggered the move. Niamh Charles scrambled her way through and the ball fell kindly to Melanie Leupolz whose dinked chip to Sam Kerr set her up before Guro Reiten hammered home to get Chelsea back in the game.

Chelsea are back in it!

Guro Reiten gives the visitors a glimmer of hope at the Nou Camp.#UWCL | #CFC

@DAZNFootballpic.twitter.com/GFF6HOJaZb

— The Athletic | Football (@TheAthleticFC) April 27, 2023

Game on. Hansen’s goal, Kerr’s effort and Reiten’s equaliser were the first three shots on target. Substitutions, Lauren James and Pernille Harder, came on as expected in the 76th minute — it was time for them to produce something special.

Chelsea dominated the second half. Barcelona were rattled so much that head coach Jonatan Giraldez deemed it “too risky” to bring on two-time Ballon d’Or winner Alexia Putellas, on her return to the squad after an anterior cruciate ligament injury — the “game was too high, open and demanding.”

Asked whether they panicked, Bonmati said: “Yes. It’s impossible not to panic. In the second half you think if they score a goal, they can draw.”

“We had to suffer for the last part of the game. You have to enjoy suffering until you can’t anymore.”

But when Barcelona were suffering Chelsea lacked composure in the build-up and the final third. They skipped a pass in a rushed attempt to hit long to Kerr, but the balls were wayward and Chelsea conceded possession.

Kerr’s hold-up play was poor, and although she won five out of her six contested aerial duels, she was heading up the pitch with no one ahead of her, allowing Barcelona to easily mop up. Harder and James, meanwhile, struggled to make an impact.

“Pernille has played no football,” said Hayes when asked about her changes. “It’s a gamble throwing her into a high intensity game.”

“You saw last week Lauren coming in for 45 minutes. There is a lot of pressure and expectation. Everyone has to be on the same page and you have to maintain a level of intensity. Stick or twist we would have still maintained the momentum. I have no regrets with anything we did today.”

Chelsea made Barcelona suffer and that is a significant accolade — no team has done that at Camp Nou. In the second-half Hayes’ team reduced Barcelona to having 51 per cent of possession. Chelsea had a superior expected goals (xG) figure (0.57 to 0.48), more shots on target (3 to 2) and more shots inside the box (3 to 2). Chelsea goalkeeper Ann-Katrin Berger had one save to make all game.

Hayes’ team showed how they could contain Barcelona but not kill them off. Ultimately, Chelsea lost this Champions League semi-final because they lost 1-0 at Stamford Bridge. “When you lose the final like we did two years ago (4-0) you can understand the first leg being a challenge,” said Hayes.

“We’ve closed that gap. This performance was indicative of the team saying ‘we’re better than this and capable of more.’”

Chelsea, having beaten holders Lyon in the quarter-finals, could not quite edge past last year’s runners-up.

Their approach nearly worked. No team has pushed Barcelona this hard in their own backyard but Chelsea needed that final ingredient. It is a balance which is so hard to develop in European competition, where games may be far and few between.

“My dressing room believes a lot more in our ability after these two games,” said Hayes. “They believe (Barcelona) are beatable.”

(Photo: Eric Alonso/Getty Images)