England manager Roy Hodgson has admitted that Scott Parker could miss Euro 2012 with an Achilles tendon injury.
The Tottenham Hotspur midfielder was named in Hodgson's 23-man squad for the tournament on Wednesday.
However, Hodgson has revealed that he may need to find a replacement if the problem does not clear up.
"Scott's had an injection which will probably take a week for us to see if it's been successful or not," he told reporters.
"He could still miss out, although from what I'm hearing, it won't be a problem. He's very confident.
"I'm very optimistic. The doctor spoke to Scott Parker and Spurs on Wednesday, so I'm confident - but I can't give a guarantee."
Liverpool's Jordan Henderson, who was named among the replacements, would be likely to take Parker's place in the squad.