Source: Dan Koppen fractures ankle

MIAMI -- New England Patriots center Dan Koppen suffered a fracture in his left ankle late in the first half of Monday night's 38-24 win against the Dolphins and was carted off the field, according to a league source.

A source told ESPNBoston.com's Mike Reiss that Koppen will undergo an MRI on Tuesday to determine the extent of the damage.

Koppen did not return to the game and was seen on the sideline wearing a protective boot. He was on crutches after the game.

"That's tough. He's the best and there's no one like him," Patriots quarterback Tom Brady said of his longtime center. "I think he and I have a great chemistry between the two of us. We always have and he's one of my great friends. Hopefully he's back at some point. We're certainly going to miss him but at the same time other guys have to step in and do the job. I think that's part of what this game's all about, other guys stepping in when they're called upon and executing just as if he was in there. Hopefully we get him back at some point."

With the Patriots facing third-and-1 at their own 19, Brady sneaked the ball for short yardage to move the chains. But Koppen got tangled at the line and teammates immediately motioned for the training staff. He was lifted onto a cart and wheeled off the field with New England's medical staff appearing to hold his left ankle steady.

The Boston Herald first reported that Koppen had broken his ankle.

Dan Connolly took Koppen's place at center. The Patriots already were thin on the offensive line with starting right tackle Sebastian Vollmer sidelined by a back injury. Rookie Nate Solder made his pro debut in his place.

New England added Thomas Welch to its 53-man roster from the practice squad before the game to add depth along the line.

Chris Forsberg covers the Patriots and Celtics for ESPNBoston.com. Information from The Associated Press was used in this report.