Razak Boukari is set to undergo on operation on his long-standing calf injury which will rule out him returning to action this season.
The highly-rated winger has been out since last September with what is a very rare injury to have affected his calf.
He was once again stepping up training on a gradual basis but has broken down and is likely to travel for Finland for surgery to hopefully resolve the injury.
“Razak is struggling,” said boss Dean Saunders.
“This is the third time he has broken down now.
“He’s going to see a specialist in Finland next Wednesday and he might have to have an operation on his calf, which will get him right for next season.
“So that’s a blow. Basically, the two calf muscles are joined but one of his has slipped away from the other one.
“Normally when you put them back, the scar tissue heals and seals them together but if the scar tissue isn’t strong enough, they go again.
“He gets to a point and he just feels it again, so they’re going to have to sew them back together.
“It’s a big blow because he’s a good player and the club paid a lot of money for him.”
Ruling out the potential of Boukari’s comeback means he joins Carl Ikeme, Dave Edwards and Bakary Sako in effectively being ruled out for the season, with Wayne Hennessey also continuing his recovery from a cruciate knee ligament injury and expected back for pre-season.