The 36-year-old forward did not practice Sunday. The Capitals had the day off Saturday.
Ovechkin was slow to get up after hitting Flyers forward Travis Konecny in the left circle of the offensive zone 9:40 into the first period. When play was stopped, the Capitals forward got up, coasted to the bench and limped to the locker room.
"Any time a player leaves the ice you're concerned," Capitals coach Peter Laviolette said.
Washington won 5-3. It opens the regular season against the New York Rangers on Wednesday (7:30 p.m. ET; TNT).
"There's always a concern," Capitals forward T.J. Oshie said. "We were kind of joking in the room there that that Russian blood, he'll be back soon. I don't know if he even misses a day. He's a tough guy. It's always concerning seeing him lay there, but no doubt he'll be back scoring goals in no time."
Ovechkin is entering his 17th NHL season. He missed an NHL career-high 11 games last season: four while in NHL COVID-19 protocol and seven with a groin injury.
He is sixth in NHL history with 730 goals, 164 behind Wayne Gretzky for first, with a chance to climb as high as third this season. He trails Marcel Dionne (731) for fifth, Brett Hull (741) for fourth and is 36 behind Jaromir Jagr (766) for third. Gordie Howe (801) is second.
"As always, they're going to be cautious and they'll reevaluate it and then we'll look to see where he's at for practice, if he's there or if he needs a little bit more time," Laviolette said of the Washington captain. "But I think there will be some sort of an announcement once we get a reevaluation on it."
Capitals center Nicklas Backstrom did not play this preseason because of a left hip injury that has bothered him since last season.
