The oft-injured winger missed practice Wednesday with what coach Randy Carlyle called a "bruised lower calf area" as a result of a collision with P.A. Parenteau of the Colorado Avalanche a night earlier.
Lupul's status for Thursday's game at the Nashville Predators is unclear, though he was set to travel with the team.
"I would say that when you say a player's day to day, it would be totally dependent upon how he feels," Carlyle said. "Hopefully the swelling (subsides) and it'll be back to normal shortly."
Lupul, who missed the start of training camp with back spasms and all but 16 games last year with a broken arm and concussion, got some treatment and rode a stationary bike Wednesday. Meanwhile, AHL call-up Josh Leivo took his place on the second line alongside Mason Raymond and Dave Bolland.
Leivo wasn't the only new face as the Leafs again spun the wheel on minor leaguers, bringing up forward David Broll and defenceman T.J. Brennan and sending Trevor Smith and Jamie Devane back to the Toronto Marlies.
The Leafs are still trying to find the right mix amid injuries to Nikolai Kulemin (ankle) and Frazer McLaren (finger) and the suspension of David Clarkson. Border-line NHL forwards Carter Ashton and Troy Bodie already have regular spots in the lineup and the team has tried Spencer Abbott, Devane and Smith to plug holes early in the young season.
"I think that we owe it to our players to be a little bit more consistent with our lineup," Carlyle said. "Our hand's been forced through some injuries and then the birth of a child (Tuesday), all those things play into it. That's the adversity you have to deal with in the NHL."
Forward Jay McClement was back on the ice with teammates Wednesday after missing the Colorado game to be his wife, Lesley, who gave birth to the couple's first child. Reid McClement is healthy and doing well, according to his father.
"The timing was tough, I definitely didn't want to miss a game for it," McClement said. "But it's not something you want to miss. I think it's one of those life experiences that I'll never forget. I was glad I was there. As much as we tried to plan not to miss any games, you can't fight Mother Nature sometimes."
Barring unforeseen changes, McClement could go back to his role as the fourth-line centre Thursday. It's quite possible that Broll makes his NHL debut on the wing.
"I'm going to appreciate it for the opportunity I've got, but it's the hard thing about staying here," Broll said. "It's one thing getting called up, but the next thing now for me is just trying to stay here as long as I can and prove myself."
Broll watched as a few former Marlies teammates played sparingly for the Leafs over the past couple of games. The 20-year-old figures that's to be expected and knows young players must earn their minutes.
That's difficult if Toronto falls behind as it did Tuesday against Colorado and Saturday against the Ottawa Senators, when Carlyle had little choice but to shorten his bench. Because of injuries, the Leafs became a two-line team that mixed in centre Nazem Kadri as much as possible and veteran enforcer Colton Orr on occasion.
It's tough to win that way, especially against opponents that are fresher early in the season. But Carlyle didn't want to make excuses.
"I can remember the Ottawa Senators last year (at) the beginning of the season, they just kept losing body after body after body and there was a lot made out of it that they were continuing to find ways, and that's what we expect out of our group," he said. "We have to find ways to have success."
Brennan was part of a similar injury situation last year, traded to the Florida Panthers after they dealt with a torrent of players going down. By the time the defenceman arrived, the Panthers "already took a real big blow."
This time around, Brennan considers the bevy of call-ups an example of organizational depth.
"Obviously it's a great honour being acknowledged for guys like Leivo and (Broll) and Abbott being called up so early," he said. "Obviously it's just something to shoot for."
Broll's mentality for earning minutes is to go shift by shift, hoping he plays well enough to earn another. That's not exactly stability, but it's reality for Leafs forwards right now.
"Hopefully one of us can just jump in and stick for a bit because they got a couple injuries right now," Leivo said. "I'm looking at it as an opportunity, not a challenge."