England captain John Terry has been ruled out Saturday's Euro 2008 qualifier with Estonia and is a major doubt for the trip to Russia next week due to a knee injury.
The Chelsea defender was sent for scans on Thursday after picking up a problem during training.
However, as the knee was badly swollen, the medical team were unable to offer a full diagnosis.
Terry, who was already set to play in a protective mask covering his fractured cheekbone, will now sit out Saturday's clash with Estonia at Wembley and seems unlikely to be fit in time to face Russia in Moscow on Wednesday.
"John Terry had a scan on his left knee today and will not be fit for Saturday's game against Estonia," confirmed coach Steve McClaren.
"He will remain with the squad and his injury will be assessed on a daily basis with a view to Wednesday's match in Russia.
"During this time the England and Chelsea medical teams have been and will be in close communication."
Meanwhile, the absence of Terry means Steven Gerrard will wear the captain's armband at Wembley.
It also means Sol Campbell is set to make his first competitive England start for two years at the heart of the defence.
The Portsmouth veteran will partner Rio Ferdinand at the back should he prove his fitness after a recent Achilles problem.