Blackburn Rovers boss Sam Allardyce has fears that defender Ryan Nelsen may have a nasty knee injury after having to come off in the game against Bolton on Sunday. The 32 year old came off worse in a clash with Bolton’s Ricardo Gardner and that has left Allardyce sweating. "I'm hoping that he's twisted his ankle and not his knee," Allardyce told the Blackburn official website. "But he was holding his knee which was the big problem for me and I think it's his one where he's had surgery before." "It'll be 48 hours before we can tell and we'll keep our fingers crossed, not just for us but for him."