The Knicks still have not revealed the specifics of Carmelo Anthony’s injury, but coach Mike Woodson said Anthony has “built-up fluid’’ in the back of his right knee.

Anthony sat out Wednesday night’s 87-77 victory against the Pistons, but Woodson did not rule him out tonight for Kevin Durant and the vaunted Thunder.

“He said he felt better,” he said. “We’ve just got to gauge it.”

Anthony didn’t attend the morning shootaround yesterday, staying back at the hotel for treatment as Woodson called him a “game-time decision.” Ninety minutes before tip-off, however, Anthony marched into the arena in a red sweatsuit and told Woodson he would not play.

Woodson did a mea culpa after Monday’s game in Cleveland, saying he kept Anthony in despite Anthony wanting out because of his bum knee. Two minutes later, Anthony crumpled to the court after taking a pass at midcourt. He got up and walked off to the locker room and didn’t return, with the club down 22 points. It caused speculation in many circles that Anthony wasn’t as hurt as he let on, but more embarrassed the Knicks were getting blown out at the time.

The Knicks — who have a history of being vague with injuries — officially have called it a “stiff/sore right knee.” A leading orthopedist from Lenox Hill Hospital, Dr. Leon Popovitz, said yesterday Anthony’s symptoms could be a bone bruise. Or it could be part of a larger cartilage issue.

Woodson said it was Anthony’s decision on whether to play through it.

“From the MRI [exam] he shows he has some fluid build-up, which is causing the stiffness,” Woodson said. “Rest will probably be the best thing for him. He’s got to make that commitment. If he wants to sit down and rest a game or two we’ll do that. It’s still a long season.”