DENVER -- Defensive end Andre Carter suffered an injury to his left leg late in the first quarter of Sunday's 41-23 win against Denver and did not return.
Carter's agent, Carl Poston, told ESPN's Josina Anderson that X-rays on his knee were negative and the early diagnosis "looks like Andre has a quad-related injury that will require surgery."
The team said Carter had a knee injury but provided no further details.
Carter was defending the run when he fell to the ground, clutching the left knee. He got attention from trainers on the field before being loaded onto a cart and wheeled off the field.
"Losing Carter was a big loss there in the second quarter, but we had guys step up and they contributed throughout the game," Patriots coach Bill Belichick said.
Carter has been one of the team's top defensive players this season with 10 sacks through the first 13 games of the season.
"That's tough. Andre puts so much in with his leadership alone. He gives a lot to this team," defensive captain Vince Wilfork said. "To see him go down is tough. Any time someone goes down it's tough, but to see a guy like that go down -- he hasn't really won a lot in his career, but now he's winning, he's happy here, he's having fun, he's playing well -- it's a blow. We had to have guys step up. We stepped up and got this 'W' for him."
Patriots defensive end Mark Anderson said that while the team prepares for playing without injured players, losing Carter is a big blow.
"It's something we work on during practice. We all get reps," Anderson said. "Losing Andre, it's a big part of our defense. Hopefully it's nothing serious, but we were able to look past that and everybody stepped up and made plays.
"Andre is usually a very vocal leader on our team, everybody looks up to him, he's been there before and he's a great player. So losing him was very critical. Everybody just stepped up."