Russia captain Andrei Arshavin is out of Saturday's 2010 World Cup qualifier against Liechtenstein and could miss the clash with Wales four days later after suffering a groin injury.
The Arsenal forward picked up the injury playing for his club in Saturday's 2-1 league defeat by Manchester United.
"Hopefully with some rest and intensive treatment we could get him ready for the Wales match," Russia coach Guus Hiddink told Reuters on Tuesday.
"It's hard to give a definite answer right now but we should know more about his injury in the next few days."
Russia, second in Group Four, trailing leaders Germany by four points with a game in hand, host Liechtenstein in St Petersburg before travelling to Cardiff to face Wales on Sept.9.
"I definitely won't be ready to play against Liechtenstein," Arshavin was quoted as saying by local media on Tuesday.
"But I think I have a good chance to play in Cardiff as we still have nine days before that match."
Russia central defender Denis Kolodin will miss both qualifiers with a hamstring problem while Chelsea winger Yuri Zhirkov remains questionable for the Liechtenstein game after just coming back from a knee injury.