Ovechkin was injured in the first period of the Capitals' 3-2 loss at the Vancouver Canucks on Monday.
"I think in the first period some time," Capitals coach Adam Oates said of Ovechkin's injury. "He told me he was a little sore and I think as the game went along he got a little [more] sore. [Tuesday] was an off day, we traveled, so he's getting checked out [Wednesday]."
Oates would not disclose the nature of the injury, but said it was not a concussion.
Ovechkin is second in the League with 10 goals, and his 15 points leads the team.
"He's obviously our key contributor and he's got a hot stick right now, so somebody else will have to step up and fill his spot," Capitals defenseman Mike Green told CSNWashington.com. "I don't know where's he's at. I think he's OK. I think this is more of a rest for him. We'll see."