Tony Caig acted as Shay Given’s understudy at Everton, but with the Irishman struggling to shake off knee and neck injuries Harper’s return would be most welcome.
He told The Journal: "My hamstring is feeling much better and the next two days will determine how close I am to making a comeback.
"It's just over two weeks since I damaged the muscle and I was told there would be a three-week recovery period.
"I'd like to think I could be back in time for Bolton but if there's any doubt then I don't think the medical staff will take the risk.
“It's very frustrating spending time on the sidelines, but it could set me back a few weeks if I rushed my return."
Two players who will be available for the Trotters’ visit on Saturday are Jermaine Jenas and Darren Ambrose who proved their fitness in Monday’s reserve victory over Wolves.