The Giants’ depth chart at offensive line has quickly flipped.

Marcus Mckethan, who has started the last two games at right guard, will remain the starter at that spot, head coach Brian Daboll said on Tuesday.

Daboll expects Ben Bredeson, who missed the Giants’ Week 3 loss to the 49ers with a concussion, to be available for the team’s Week 4 clash against the Seahawks at MetLife Stadium Monday night, though the team later clarified that Bredeson is still in the concussion protocol. If he’s ready to go, Bredeson will start at left guard.

It’s a major step for McKethan, who the Giants drafted in the fifth round last year but missed the entire season after tearing his ACL in the summer.

“I think he’s done a good job,” Daboll said Tuesday. “Again, he’s only played a couple games, he was out all last season. Improving. Big body, moves well, the experience that he’s played in the first couple of games will help him.”

But as much as it means for how the Giants view McKethan, it likely says more about what they currently think of Mark Glowinski.

The Giants have effectively benched Glowinski, barely into his second season after signing a three-year, $20 million deal to be a bona fide starter.

He played every snap at right guard and struggled mightily in the team’s Week 1 blowout loss to the Cowboys. He was subsequently removed from the starting lineup for the Giants’ Week 2 comeback win over the Cardinals, and played just 37 offensive snaps (54 percent) before not playing at all in the Week 3 loss to the 49ers.

With Bredeson sidelined against the 49ers, the Giants opted to start Shane Lemieux at left guard, the first time he played an offensive snap since Nov. 20, 2022.

The two guard spots were constant question marks throughout training camp, with Bredeson, Glowinski and Joshua Ezeudu rotating. In their first unofficial depth chart ahead of Week 1, the Giants listed Bredeson and Glowinski as the two starting guards, and McKethan as the third-string right tackle.

McKethan now resides atop that depth chart at a different position, with Glowinski seemingly buried.

It also appears McKethan has surpassed Ezeudu, who started the last two games at left tackle for the injured Andrew Thomas.

Ezeudu could have slotted in at right guard if Thomas is available, but it’ll be McKethan again instead. Daboll said Ezeudu can now provide insurance at four offensive line spots — everywhere but center.

Ezeudu and McKethan were teammates at North Carolina and drafted by the Giants in the same class, presenting an interesting dynamic for their positional battle.

“I love Marcus,” Ezeudu said. “He’s very good. We both know that he is good and can be very special, too. I love him. … He’s a very nice person, too. I know I can call him and tell him about everything. He’s my best friend.”