Mitchell Marner left practice early Tuesday after taking a hit from Wayne Simmonds, and the forward will be reevaluated Wednesday, coach Sheldon Keefe said.
"He had a bit of a glancing blow there with Simmonds on the ice," Keefe said. "It's just precautionary at this point in time; we will re-evaluate him in the morning and take it from there."
The Maple Leafs will open the regular season at home against the Montreal Canadiens on Wednesday (7 p.m. ET; SN, TVAS, ESPN+, NHL LIVE).
Marner had the puck in the slot and was trying to sidestep Simmonds, who caught Marner with a hit to the front of his body.
Forward Jason Spezza said he did not think Marner's absence for the second half of practice was due to a serious issue.
"Not really concerned," Spezza said. "I think it was just precautionary, he probably wanted a rest. I think he'll be fine, I haven't talked to him so maybe I shouldn't make light of it, but it did seem like it was a pretty minor thing." -- Dave McCarthy