Kayvon Thibodeaux’s official Giants debut might be delayed.

Thibodeaux is expected to miss three to four weeks after he was diagnosed Monday with an MCL sprain in his right knee, The Post confirmed. The Giants, who open the regular season in 20 days on Sept. 11 at the Tennessee Titans, dodged the worst-case scenario from the rookie edge rusher’s early exit in Sunday’s game when an MRI revealed that his ACL and meniscus remain intact. Surgery is not needed.

“Fingers crossed that his rehab goes well and he can get out there as soon as he can,” head coach Brian Daboll said.

Cincinnati Bengals tight end Thaddeus Moss — the son of Hall of Famer Randy Moss — cut-blocked Thibodeaux inside the tackle box as he came across the formation during the second quarter. The No. 5 overall draft pick writhed in pain for a minute but walked off the field under his own power, joked with teammates on the sideline after emerging from the medical tent and disappeared into the locker room.

Daboll absolved Moss of a dirty or illegal play.

“Those are tough blocks,” Daboll said. “You have to see it, and then you have to do a great job of trying to play it with your hands. It’s unfortunate that K.T. went down, but it’s part of the game.”

Thibodeaux declared “all good news” on his health to media after the game. A more accurate assessment would’ve been not all bad.

“The reason why he didn’t end up with an ACL or a fracture or a worse sprained MCL is that, although his foot was planted, his knee was bent in a [loose] open-pack position,” Dr. David Chao of SICscore.com told The Post. “He is able to walk off and not have any problems because he is going straight ahead versus side-to-side. If he has to push to get around a corner, he can’t really do it right now.”

Thibodeaux’s final tally for the preseason includes one tackle and one quarterback pressure on 31 snaps. He will miss the final week of training camp but will count against the 53-man roster on cut day. Players placed on injured reserve before Aug. 30 cannot return this season. An IR designation after Aug. 30 requires a minimum three-game absence.

“K.T. has done everything we’ve asked him to do since he’s been here — been a good teammate, worked extremely hard,” Daboll said. “Certainly you never want to miss some time, but he has the right attitude and the right approach.”

What will Thibodeaux’s rehab look like? The Giants are unlikely to push their prized draft pick and risk long-term damage in what is seen as a rebuilding year.

“I expect to see him on an exercise bike. I expect very soon to see him jogging and running straight ahead. That will happen well ahead of Week 1,” said Chao, an orthopedic surgeon and former Chargers team doctor who correctly forecasted Thibodeaux’s diagnosis from video after it happened. “He will come back more quickly at left end than at right end because the outside leg is how you get around the edge.”

The Giants for now are back to a similar group of edge rushers to what was in need of an upgrade last season: Azeez Ojulari — who “looked good for the first time out there” in forcing two holding penalties on seven snaps after returning from a hamstring injury — on one side and a mix of Oshane Ximines, Quincy Roche, Jihad Ward and rookie Tomon Fox (17 sacks combined in 112 career games) on the other.

“All those guys have really done a good job of understanding our system,” Daboll said, “and making the most of their opportunities.”

Chao does not expect Thibodeaux’s injury to linger after rest allows for a full recovery, which he estimates as “can’t guarantee” by Week 1 but likely by Week 3.

“The MCL always heals with a little bit of laxity, but it’s nothing to be worried about,” Chao said. “Will the knee always be a tiny bit looser? Yes, but it shouldn’t nag or be a long-term issue at all once it’s healed.”