Boston Bruins coach Jim Montgomery had a night to sleep on his team’s 2-1 overtime loss to Toronto in Game 5 of their first-round Stanley Cup playoff series on Tuesday — and remained in a foul mood about it by Wednesday.

“I’m still pissed off from last night, to be honest,” Montgomery said after the Bruins’ optional practice. “I don’t understand and don’t accept our play last night. I’m going to be pissed off until the puck drops [in Game 6].”

The Bruins entered Tuesday’s game with a 3-1 lead in the best-of-seven series and could have eliminated the Leafs with a victory on home ice. Instead, Boston is headed back to Toronto for Game 6 on Thursday knowing the Leafs have life again.

Montgomery brought his group in prior to the trip for a meeting where the Bruins went over a lackluster Game 5 performance that included a costly, poor start and a general failure to match the Leafs’ urgency.

Boston allowed Toronto defenseman Jake McCabe to open the scoring in a first period where the Bruins were outshot 11-2. Even though Trent Frederic capitalized on a fortuitous bounce to tie the score at 1-1 through 20 minutes, Boston was on its heels in Game 5 more than they had been throughout the series. Matthew Knies‘ overtime winner just 2:26 into the extra frame was a dagger Montgomery couldn’t shake.

“We wanted to review the game and where we went wrong,” said Montgomery. “We started talking about where we need to get better. Some of that’s physical. Some of it is mental. Some of it is staying in the moment. I don’t think we did a good enough job staying in the moment last night. That’s what we’re looking for [in our] next game.”

Montgomery also took heat for altering his lineup in Game 5. Rather than sticking with what previously worked, Montgomery inserted Matt Grzelcyk for Kevin Shattenkirk on the blue line — and watched Grzelcyk be victimized by John Tavares‘ foot speed setting up Knies’ winner in overtime.

“There are a lot of discussions that go on, but in the end, I end up making decisions that I was really confident were best for the Boston Bruins,” said Montgomery. “And when it doesn’t work out, I understand it’ll be second-guessed and third-guessed and fourth-guessed. I understand that it comes with the territory. Just like when you make changes, and it works out. It’s the same thing. But I’m comfortable with the decisions I made and why I made them, and the criticism that comes with it.”

The Bruins’ missed opportunity to polish off the Leafs puts them in uncomfortably familiar territory. Last spring, Boston was the league’s reigning Presidents Trophy winner and jumped out to a 3-1 series lead over the eighth-seeded Florida Panthers. The Bruins failed to close out the Panthers in three straight tries and unraveled entirely with a stunning first-round playoff exit.

Boston has done well this time around as the road team, taking both Game 3 and 4 in Toronto that put the Leafs on the ropes. Toronto has lost six consecutive postseason games on home ice and was booed by its own crowd after a dismal two-period effort in Game 4 on Saturday. A seventh consecutive defeat in their building on Thursday would spell the end of another disappointing Leafs postseason.

That’s why Toronto coach Sheldon Keefe stressed the importance of his team keeping Thursday’s game in perspective, focusing on what they could build from rather than worrying about the venue.

“Quite honestly, [being home again] means nothing,” he said. “We have to approach the game no differently than we have on the road in terms of our plan and what’s required. We don’t have to impress anyone. We don’t have to do this or that, we have to win a game.”

Toronto made a significant lineup change of its own Tuesday, starting Joseph Woll for the first time in this series over Ilya Samsonov. Woll was excellent in making 28 stops and projects to get the call again in Thursday’s critical matchup. Less clear is whether the Leafs will have forward Auston Matthews back in the lineup.

Matthews missed the third period of Game 4 and all of Game 5 with what the Leafs have deemed a “lingering” illness. He skated Tuesday and again Wednesday, but Keefe provided no update on whether he would be available to play in Game 6. Max Domi took over Matthews’ top-line spot in Tuesday’s win with good success (one assist, 85.7 faceoff win percentage) and would center there again if Matthews can’t go.

Boston had better news on Brandon Carlo, who was absent from their bench in overtime Tuesday. Montgomery confirmed the blueliner will be “good to go” in Game 6.

However the Bruins’ lineup comes together, the Leafs are preparing for another hard-fought bout Thursday to keep their season alive. But now, Toronto has a blueprint in mind for success.

“We’re still in a battle,” said Keefe. “That certainly has not changed. We’ve gotten the opponent’s attention here now. So, tomorrow is going to be an even tougher night, but there’s one way to go about it. And that’s how we’ve played in our last two road game [wins]. That’s playoff hockey. That’s what’s required, and we have to bring that to the ice tomorrow.”