Lang is out indefinitely after hurting himself in a game against the Boston Bruins on Sunday afternoon. ((Graham Hughes/Canadian Press))

Montreal Canadiens' forward Robert Lang had successful surgery to repair the Achilles tendon in his left leg, the team announced on Monday.

Lang was hurt on an innocent-looking hit on Stephane Yelle during the game against Boston on Sunday afternoon. The 38-year-old cut the Achilles tendon in his left leg on a skate, forcing him to leave the game. He had surgery on the injury late Sunday night.

There's no timetable for his return, with the Habs only saying that he's out "indefinitely," but early reports from other sources say that he could be out for three to four months, essentially ending his season.

It would be a huge blow for Montreal if that's true. Lang has been one of the team's steadiest performers since he came over from Chicago in the summer. The veteran leads the team in scoring with 18 goals and 21 assists in 50 games so far this season.

And that's not the only bit of bad news that could happen to the club, which is still waiting on the status of winger Guillaume Latendresse, who also left Sunday's game with an apparent shoulder injury.

Montreal sits fourth overall in the Eastern Conference but are only one point away from falling to sixth.

With files from the Canadian Press