Blackburn Rovers captain Ryan Nelsen is likely to be out for a month with a hamstring injury.
The defender suffered the problem during Rovers' surprise 2-0 defeat to Larissa in the Uefa Cup on Thursday.
He was replaced early in the second half by Zurab Khizanishvili and is expected to be absent for the next four weeks.
"It's the hamstring he had the operation on," said Rovers boss Mark Hughes.
"A little bit of the scar tissue has released itself, and in the long term he will be better for it, but in the short term he is likely to miss the next three or four games."
Nelsen will now sit out the second leg of the Uefa Cup first-round tie with Larissa at Ewood Park in a fortnight.
The New Zealand international will also miss next week's Carling Cup game with Birmingham City, and is tipped to return for the 20th October fixture with Reading in the Premier League.