The Vegas Golden Knights find themselves facing a must-win Game 6 in Montreal on Thursday after losing 4-1 to the Canadiens on Tuesday night.

Golden Knights head coach Peter DeBoer had little by way of explanation for his team's Game 5 loss, in which they trailed 3-0 after two periods.

"Hard to explain. We didn't have great legs, didn't have great execution," DeBoer said. "You have to give them credit. I thought they played a real good road game. And then obviously falling behind early against that team is tough. That's not a formula for success, we've shown."

Vegas is playing in the third round for the third time in their first four NHL seasons, but the team is on the brink of falling short of the Stanley Cup Final for the second straight season.

"It's best-of-7 for a reason," defenceman Brayden McNabb said. "We didn't play good at all today. We played right into their game; we didn't play our game at all."

The Golden Knights went back to Marc-Andre Fleury in net Tuesday after Robin Lehner backstopped the team to a 2-1 overtime win in Game 4. Fleury made 22 saves on 25 shots in the Game 5 loss and it's unclear who will start with the team's season on the line Thursday.

The Canadiens, meanwhile, can clinch their first trip to the Final since winning the Stanley Cup in 1993 with a Game 6 win.