Now, he has an even bigger problem than inconsistent play.
The Sabres (10-6-0) had their four-game winning streak snapped with a 6-2 loss to Boston on Saturday, as Miller allowed three goals on 22 shots before Enroth replaced him for the third period.
Miller, 1-5-0 with a 4.16 goals-against average in his last six starts, initially stayed in the game after a first-period collision with Boston's Milan Lucic, who received a minor penalty for charging.
Buffalo's goalie had strayed from the crease to play the puck, and he was livid with Lucic after the game.
"(Lucic has) 50 pounds on me and he runs me like that? It's unbelievable," Miller said. "Everyone in (Boston) sees him as a big tough solid player. I respected him for how hard he played. That was gutless. Gutless."
The Sabres revealed the nature of Miller's injury Sunday.
Buffalo can at least feel good about turning to Enroth, who has gone 5-0-0 with a 1.75 GAA in seven games - five starts - this season despite allowing three goals on 13 shots in the third period Saturday. The club recalled Drew MacIntyre from Rochester of the AHL to back up Enroth.
Miller made 40 saves in a 3-1 win at Montreal on Oct. 18, part of the Canadiens' 1-5-2 start. However, the club seems to have put those early struggles behind it.
Montreal (7-7-2) has won six of eight since those first eight games, during which it scored one or no goals five times.
The Canadiens have found their scoring touch and tightened up their defense in front of Carey Price, who has gone 5-2-0 with a 1.86 GAA in his last seven starts.
It was the second straight OT victory for Montreal, which beat Phoenix 3-2 on Thursday.
"It's been a few games now that we've been working really hard around the net but weren't scoring much," Desharnais told the team's official website. "It was great to finally be paid off."
Price likely will be back in net against Buffalo, a team he's performed well against while not always receiving enough offensive support. He hasn't allowed more than two goals in his last 10 starts versus the Sabres, though he's gone 4-3-3 in those matchups despite a 1.47 GAA.
Buffalo's Thomas Vanek, who has three goals and an assist over his last three games, scored the winner against Price in the second period last month.
The Canadiens' Andrei Kostitsyn missed his third straight game with a lower-body injury Saturday, and it's uncertain if he'll be in the lineup against the Sabres.
Buffalo has won three straight and six of the last eight meetings in Montreal.