Cleveland Browns vs Pittsburgh Steelers

Cleveland Browns center Alex Mack is supported by his teammates after being injured on the field against the Pittsburgh Steelers in the second quarter of the Browns' 31-10 win Sunday.

(John Kuntz, The Plain Dealer)

CLEVELAND, Ohio - Browns two-time Pro Bowl center Alex Mack suffered a broken fibula in his left leg in Sunday's 31-10 victory over the Steelers and is likely lost for the season, a league source told cleveland.com.

"It's huge,'' said guard John Greco, who replaced Mack and could get the nod at center for the rest of the season. "He's one of the best players I've ever seen. We wish him the best. They definitely are hard shoes to fill, but I have to go in and try to do my job.''

Said left tackle Joe Thomas: "It was pretty emotional for me. We've played every snap together for six years …. I was shocked to see a smile on his face. That just says everything you need to know about him. He is the most unselfish guy I know.''

Added Greco: "I know he'll be back stronger than ever. He'll probably come back faster than anyone can.''

Coach Mike Pettine said the victory was tempered by the loss of Mack and defensive end Armonty Bryant, who hobbled out on crutches and wearing a big brace on his right knee.

Mack's leg was immediately immobilized in an air cast and he was carted off the field. He raised his hand to fans on the way off but wore a pained expression on his face.

Mack had started all 85 games since he was drafted in 2009 and had never missed a snap. John Greco replaced him at center. Paul McQuistan took over Greco's former spot at starting right guard.

Mack suffered the injury on a 3-yard run to the right by Isaiah Crowell late in the first half. The Browns went on to finish the drive with an 8-yard Ben Tate touchdown run that gave them a 21-3 lead with just less than three minutes left in the half.

The Browns made the two-time Pro Bowler the highest-paid center in the NFL this past offseason when they signed him to a five-year, $42 million contract, including $26 million guaranteed. Mack's base salary in 2014 is $10 million.