Frank Lampard has emerged as a doubt for England's vital Euro 2008 qualifiers against Israel on 8 September and Russia four days later.
Lampard scored for England in the 2-1 loss to Germany
Lampard, 29, has a thigh injury and will miss Chelsea's Premier League game against Aston Villa on Sunday.
"We can confirm Frank Lampard was injured in training on Friday," read a Chelsea statement.
"A scan has shown he has a tear in his left thigh. It is too early to say how long it will keep him from playing."
The club added: "The injury is on the same leg as the toe he broke earlier this season."
Liverpool midfielder Steven Gerrard is also a doubt but is expected to play.
Gerrard, 27, is suffering from a hairline fracture of the toe and will miss Liverpool's game against Derby.
Coach Steve McClaren's plans had already been hit by injuries to David Beckham and Kieron Dyer.
McClaren said: "I have spoken to Steven and I am very confident he will be available.
"He did play against Chelsea a couple of weeks ago and obviously we will take medical advice before making a decision.
"But ultimately, Steven wants to play in the next two games. He knows how important he is to our team. We need him."
Gerrard took pain-killing injections to play against Chelsea two weeks ago, but Liverpool boss Rafa Benitez did not risk him against Sunderland and Toulouse last week.