The 29-year-old limped off just before the hour during the 2-0 first round first leg-defeat by the Greek Cup winners at the Panthessaliko Stadium in Volos.
Manager Mark Hughes told the club´s official website, www.rovers.co.uk: "It is the hamstring that he had the operation on but we think it is a bit of scar tissue that has released itself."
Copyright (c) PA Sport 2007, All Rights Reserved.
Do YOU want to write for GiveMeSport? Get started today by signing-up and submitting an article HERE: http://gms.to/writeforgms