Bolton's highly-rated full-back Joey O'Brien could be ruled out for the whole season.

The Republic of Ireland international is undergoing a rehabilitation programme following knee surgery and is not expected to resume training for another three to four months.

O'Brien, 20, has not featured for Bolton in the current campaign after suffering the setback in pre-season.

Sam Allardyce initially thought the defender would be available for part of the festive programme but those hopes have been dashed.

The Bolton boss said: "Joey is really distraught. When he finished here last year he was on a high after playing 28-30 games.

"Then before the season got under way, he was stricken by an injury that has become increasingly worrying.

"He has experienced the accolades, now he is experiencing the cruelty of the game.

"Joey is on a rehabilitation programme and is going to be out for another three to four months.

"As he has had surgery we have to make sure we get this injury 100% right for his long-term future. It should stand the lad in real good stead."

Allardyce is forced to make at least one change to the side that defeated Aston Villa when Bolton face Manchester City on Saturday.

Kevin Davies is suspended but could be replaced by El-Hadji Diouf, who returns after a ban.

Ricardo Gardner is pushing for a place in the starting line-up after being on the bench at the weekend.

The Jamaica international, who has recovered from knee surgery, had a run-out for the reserves last night.

Allardyce said: "The pace of the Premiership was a little bit of a shock to Ricardo at the weekend.

"It is good to see him back with the group and slowly but surely we will get him back to his best."