Celtic summer signing Steven Mouyokolo will be out for six months with a complete rupture of an Achilles tendon, manager Neil Lennon has confirmed.
The 26-year-old defender returned to France, where he has had surgery on the injury picked up at training on Monday.
"It was an innocuous thing," said Lennon. "He was running for the ball and we heard this pop.
"We thought he had clipped someone's ankle, but obviously straight away he knew something was wrong."
Mouyokolo has made two starts since signing for the Scottish champions in July following his comeback from a cruciate ligament injury.
"He had a complete rupture of his Achilles tendon, he has had surgery in France," said Lennon.
"We are waiting on how well the operation went, but we are looking at maybe six months, so we are hoping to see him sometime in the new year."
Mouyokolo was a free agent after his contract with Wolves was terminated by mutual consent in January.
with Celtic after impressing on trial during their pre-season trip to Germany and Austria.
"It is devastating for him," added Lennon. "He has worked so hard.
"This is a totally separate injury to the previous ones he had. It can happen to anyone at any time.
"He has just had horrendous luck and he will support him all the way and hopefully we can get him back up and running in February or March."
Despite the loss of Mouyokolo, Lennon insisted he is comfortable with the strength of his squad ahead of the Champions League group stage.
Celtic sold three of their top performers from last season - Victor Wanyama, Gary Hooper and Kelvin Wilson - during the summer.
However, Lennon believes his summer replacements stand Celtic in good stead for the European campaign.