The Tampa Bay Lightning will be missing a key player in Tuesday night against the Habs -- forward Ryan Callahan is out for the foreseeable future after undergoing an emergency appendectomy.

Callahan did not practice Monday. He was admitted to a local hospital Monday night and was diagnosed with acute appendicitis, necessitating the surgery.

“He’s a leader on our team. He’s extremely important, he plays with passion, grit, he plays with all those things that help you win,” said Coach Jon Cooper.

The 30-year-old Callahan hasn’t collected any points in the series but has a team-best plus-7 rating in the 12 playoff games he’s suited up for, and has taken it upon himself to make PK Subban’s life more difficult by finishing checks and rushing him on plays.

“Obviously it’s tough for Cally but we’ve got some guys who are capable of telling up in these kinds of situations. We’ve had lots of depth on our team all year,” said Steven Stamkos.

Jonathan Marchessault, who has been with the Bolts since his AHL team was eliminated from the playoffs, will likely take Callahan’s place in the lineup.

The Canadiens once again will be playing for their playoff lives tonight in Florida, but Coach Michel Therrien says he has confidence in what he called a “special” group of players.

“We don’t feel pressure right now, we apply pressure. The guys feel good about themselves, they love the challenge and this is a group that refuses to die,” he said.

The Lightning have shown an ability to overcome adversity. They trailed Detroit 3-2 in the opening round, won Game 6 on the road and returned home to beat the Red Wings in Game 7.

But in this scenario, the Canadiens are the team that is now warming up. Lars Eller said he believes this will be their toughest test yet.

“We played our best hockey of the season in this series. Now we’re starting to get the results. At the same time, once this game starts, whatever happened in the past doesn’t matter,” he said.