TORONTO -- Game 5 has suddenly become Game 7 for the Toronto Maple Leafs.

After taking an overtime punch to the gut on Wednesday night, the Leafs headed to Boston on Thursday trailing the Boston Bruins three games to one in their first-round series. Game 5 goes Friday.

"This series isn't over, for sure," winger Joffrey Lupul said defiantly after the 4-3 loss at the Air Canada Centre.

Toronto will have to mount its comeback without tough defenceman Mark Fraser, who underwent surgery to repair a fracture between the eyes and the cranial area after taking a Milan Lucic shot to the face.

Toronto coach Randy Carlyle says the burly blue-liner was resting at home and had been texting and talking to his teammates Thursday morning.

"He's a well-respected guy in our locker-room," said captain Dion Phaneuf. "He's done a great job all year for us physically, playing big minutes.

"He's just a great teammate. It was a scary situation but we're glad he's doing OK."

John-Michael Liles, a healthy scratch in recent games, is expected to take Fraser's place in the lineup in the do-or-die game at Boston's TD Garden.

"It's all about winning that game. It's like a Game 7," said forward Clarke MacArthur. "We win that one, it can turn things around."

It's a tough ask. The playoff-savvy Bruins are 15-2 when leading a best-of-seven series 3-1. Toronto is 2-12-1 in its last 15 games in Boston.

As is their wont, the Leafs looked for positives in the wake of Wednesday's loss.

"Everything becomes more difficult. But it's not the end of the world," said Carlyle. "We've done a lot of good things."

"It's a new day," said forward Mikhail Grabovski, who has played well while putting his slight body on the line.

They took an early lead against the Bruins, registered an eye-popping 71 hits and bombarded Tuukka Rask with 48 shots. And Matt Frattin hit the goalpost in overtime.

"It quite easily could be a 2-2 series right now," said MacArthur. "It's unfortunate that it isn't."

"(Wednesday) night we had our chances to win the game," said forward Jay McClement.

The coach admitted the loss hurt.

"But the bottom line is you can't change what happened last night," Carlyle told reporters at the team's training facility before flying out to Boston. "Now it's time to regroup and that's what we're here to do. Gather this group together -- reset, refocus, re-energize. Do all those things we normally do.

"We've got to go in and win a game in Boston."

That involves raising their game, while ignoring the effects of a physical series that has seen Toronto outhit Boston 200 to 165.

"Our team has got to find a way to play to a higher level," said Carlyle. "With the level of game that was played (Wednesday) night, both teams are going to be tired. Both teams are going to be bruised up."

On the minus side Wednesday, the Leafs gave up a 2-0 lead and Phaneuf was punished in overtime for pinching in and trying to get Nathan Horton and/or the puck. The Bruin, who was flattened on the play, got the puck past the Leaf defenceman and David Krejci went on to beat James Reimer on a two-on-one.

MacArthur called it a tough break.

"We didn't lose the game on that play," he said, ignoring the fact that they actually did.

"We had a 2-0 lead in that game. There's other things that could have prevented it from getting to that situation."

As he did after the game, Phaneuf emerged Thursday to face the music. Once again, he took responsibility for "a split-second decision."

"Playoffs are about momentum and obviously that was a momentum swing," he said. "But we've got a big game there on Friday, we've got to move past this and move past (Wednesday) night's loss."

"There's no time to sit here and feel sorry about what happened," he added. "It's done now and we've got to focus on Friday."

Carlyle chose not to dwell on the mistake.

"In reality, if you look at the way Dion's played for our hockey club, he's represented our team as a captain, he's played 30-plus minutes, he leads our team in a lot of different categories -- and emotionally and physically on the ice.

"Without him, we wouldn't be here."

Only a handful of Leafs hit the ice Thursday at the team's training centre: backup goalie Ben Scrivens and recent scratches Joe Colborne, Frazer McLaren, Ryan Hamilton and defenceman Jesse Blacker, who has been brought up from the AHL Marlies as defensive cover.