Lupul "tweaked" the injury in Tuesday's victory over the Colorado Avalanche, according to coach Randy Carlyle. After skating by himself Thursday morning, the 31-year-old winger left the ice before the full team workout.
"We are having an assessment done," Carlyle said. "We felt it wasn't something that was too serious ... and that was the plan, to have him skate by himself and then not join our group for today's practice. We're trying to set our sights on tomorrow."
Lupul, who missed time last season with foot and groin injuries, did not speak to reporters.
With Lupul unable to practise, Brandon Kozun moved up to the second line alongside Daniel Winnik and Nazem Kadri. That trio could remain together Friday, with Kozun bringing his speed to go along with Winnik's edginess and Kadri's playmaking ability.
"I think it's all about being versatile," Kozun said. "That's something that I want to bring to the team. I think that's something that helps me in my game that I'm able to play with all different kinds of players and play certain styles."
However, the Leafs are weaker without Lupul, who has two goals and an assist through four games. He had the tying goal in the third period against the Avalanche.
"(He's) a bona fide goal scorer," Winnik said. "You saw it the other night and you've seen it throughout his career. He scores goals and timely goals. When you miss a guy like that out of the lineup, other guys (have) got to step up and score."
The top line of James van Riemsdyk, Tyler Bozak and Phil Kessel is the engine that makes Toronto's offence churn. But Carlyle has stressed the desire for three offensive lines, and Lupul, Kadri and Winnik have been a part of that since being put together Sunday in New York.
"I'm good on the forecheck and get in on pucks," Winnik said. "Me doing that creates offensive-zone time for them. They're both really creative with the puck and highly-skilled guys. I really just work as hard as I can for them to get loose pucks."
Winnik's job won't change if Lupul can't play. Kozun's doesn't, either, even though he'd likely get some more ice time with the more prominent role.
"I just show up to the rink and try to work my hardest, and whoever I play with I'll do my best," Kozun said. "I'm not going to say I'm going to play better with these guys or those guys. I'm just trying to become a better player and that's the only thing I can do."
Notes: James Reimer and Jonathan Bernier are expected to split the home-and-home set against the Red Wings, which wraps Saturday at Joe Louis Arena in Detroit. It wasn't clear which netminder would get the nod in the opener at Air Canada Centre. ... Red Wings forward Gustav Nyquist scored Wednesday night against the Boston Bruins to become the third player in the past five seasons with 35 goals in his first 100 NHL games. The other two are Jeff Skinner of the Carolina Hurricanes (38) and Taylor Hall of the Edmonton Oilers (36).
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