The forward is day to day with an upper-body injury.
After being stopped on a breakaway, Ovechkin tripped on the stick of Toronto goalie Erik Kallgren and crashed into the boards shoulder first. He stayed down briefly, then skated off, went to the locker room and did not return 2:03 into the period.
"I just talked to him and I think he'll be all right," Capitals forward T.J. Oshie said. "It's always scary seeing 'Big 8' go down and lay on the ice. He's a tough guy. If there was anyone I would imagine wouldn't miss any more time than he needs to, it'd be 8."
Capitals coach Peter Laviolette said after the game he hadn't talked to the team trainer yet and Ovechkin was being evaluated.
Toronto trailed 3-1 in the third and was able to force overtime before winning the shootout in seven rounds. Alex Kerfoot scored the deciding goal.
"It was a real gutsy effort for the guys to find a way there," Maple Leafs coach Sheldon Keefe said. "We didn't have much today. It seemed like we were playing on fumes most of the night. We were encouraging the guys at 3-1 not to except their fate and keep pushing."