Washington Capitals forward Alex Ovechkin was taken to a hospital with a right leg injury Sunday after colliding with an opponent during Russia's game against Germany at the ice hockey world championships.
Ovechkin took a hit to his right knee from forward Marcus Kink midway through the third period but played on for several minutes before he needed assistance to leave the ice.
Ovechkin struggled to put weight on his right leg and did not return to the game, which Russia won 3-0.
Kink was not penalized for the incident.
Russia coach Oleg Znarok said he could not "share any information now" about the injury, and that more details would be disclosed after Ovechkin was examined.
The Capitals said in a statement their medical staff was "working with Ovechkin and Team Russia to gather additional information."
Ovechkin has scored three goals and added six assists for Russia in the tournament.
"It is an unfortunate incident and we hope he is OK," Germany coach Pat Cortina said. "He is a great player and a great ambassador for the game of ice hockey. We need players like that and hopefully he will be fine and we'll see him back on the ice soon."
Russia is waiting for the arrival of another star forward, Evgeni Malkin, who agreed to join the team at the worlds after his Pittsburgh Penguins were eliminated from the NHL playoffs by the New York Rangers. Malkin could be available for Tuesday's final group-stage game against Belarus.
Russia is the only unbeaten team in the tournament.