TORONTO -- Auston Matthews' status is "yet to be determined" for the Maple Leafs when they try to stave off elimination in Game 5 of their first-round Stanley Cup playoff series against Boston on Tuesday.

Matthews has been battling an illness that he was able to play through in Game 3 and the first two periods of Game 4 on Saturday. Toronto's team doctors ultimately pulled Matthews from the third period of Saturday's 4-2 Leafs' loss, which put the Leafs down 3-1 in the best-of-seven series.

Toronto's top center did not practice with the team Monday but was expected be on the trip to Boston. A decision will be made at some point before Game 5 whether Matthews is healthy enough to play.

"Of course, we're hopeful that he's available and feeling good and back to himself," coach Sheldon Keefe said. "That's what we're hopeful for. But we've played well with guys out in the past. We started the series without [William Nylander] and had to deal with that. But we'll see what tomorrow brings."

Matthews has one goal and three points in the series, including Toronto's game winner in Game 2. The illness has kept Matthews from being a full participant in all but one of the Leafs' on-ice sessions since then as they've tried to get him healed. Keefe said Sunday that the issue is how this sickness has "lingered" and becomes worse when Matthews exerts himself in a game.

Given that Matthews was unable to finish out Game 4, Toronto practiced Monday as if he wouldn't be in the lineup. Max Domi took over Matthews' spot centering the top line with Mitch Marner and Tyler Bertuzzi, while Nylander moved up to the second line with John Tavares and Matthew Knies. Domi also worked on the Leafs' top power-play unit at practice, a special teams sore spot for Toronto in the series at just 1-for-11.

Matthews is coming off a tremendous regular season where he notched 69 goals and earned a third Rocket Richard Trophy in four years as the league's top goal scorer. Though his postseason production has slowed, his absence would create a void and teammates are resigned to forging ahead without him if needed.

"It's not ideal ... to be without Auston Matthews," Tavares said. "You're talking about one of the best players in the world. But there's tremendous depth, talent and character on this team and it's a great opportunity for all of us to step up, raise our game, which is already needed and necessary."

Keefe slotted Domi onto the top line when Matthews exited Saturday and the third period was the Leafs' best of the night (although they already trailed Boston 3-0 going into that frame). It was an "easy decision" for Keefe to put Domi back there and allow the veteran to try to ignite more offense from linemate Marner (who has just assists in the series).

"[Domi's] played center for us a lot this season," Keefe said. "He's done well with Mitch, he's done well when we've had guys out, whether it was Auston or John, when they've been out Max has played in that spot and he's done a nice job for us. He's a very versatile guy, he can do different things and play different positions and with different types of players."

The Leafs' coach was less forthcoming about who would be between the pipes for Toronto in Game 5. Ilya Samsonov started all four games, but Keefe pulled him in favor of Joseph Woll for the third period in Game 4 after Samsonov gave up three goals on 16 shots, including a dagger from David Pastrnak in the final minute of the second. Woll made five saves in relief of Samsonov.

"We'll find out tomorrow," Keefe's responded when asked who would get the call in net. But he also stressed the importance of balancing the scales against Boston with better netminding and special teams than Toronto has showed in the series. The Bruins are 6-for-13 on the power play and Jeremy Swayman -- who has started three of the four outings for Boston -- has a .956 SV% and 1.34 GAA to go with his 3-0-0 record. Linus Ullmark started Game 2 in the Bruins' lone loss.

"They've had the edge in those areas in the series and that's tough to overcome. We got to take steps there," Keefe said. "Getting more saves at critical times is a big part of that. They're obviously getting lots at the other end."

Boston also practiced Monday, but without captain Brad Marchand or Danton Heinen. Coach Jim Montgomery said both players took maintenance days. Injured forward Justin Brazeau and defenseman Derek Forbort are also "an option" for the Bruins in Game 5 but Montgomery acknowledged some concern in possibly putting Forbort in midway through a series after he'd been sidelined since March 2 with a pair of ailments.