Tyrone Mears faces a fresh spell on the sidelines after suffering another setback in his recovery from a broken leg.
The 28-year-old joined Bolton from Burnley last summer but sustained the injury in training just days later.
He finally made his debut for Wanderers in their 2-0 Premier League defeat at Norwich, but it left him in pain once more and he has returned to the treatment table.
Bolton boss Owen Coyle confirmed: "Tyrone Mears has had a setback in his recovery from his fractured leg.
"He has had to have a screw replaced and he will be out for a number of weeks on the back of that.
"He came back and played at Norwich and, within playing, there was discomfort.
"Each day Tyrone trained after that, he was getting pain which was bearable to a point, but if a player goes out to play and they know there is something at the back of their mind, then it is difficult for them to make sure they are focused.
"Tyrone wants to be 100% focused with no distractions and, when the medical people looked at it, they felt that was the best course of action."
Trotters forward Kevin Davies will also miss this weekend's FA Cup clash with Millwall due to a medial ligament problem he picked up in last Saturday's 2-1 home loss in the league to Wigan, although Coyle is optimistic the 34-year-old will only be out for one game.