Celtic have revealed that defender Dedryck Boyata is to miss the next three months with a medial ligament knee injury.
The 26-year-old, who joined from Manchester City two years ago, sustained the damage during the first half of the Bhoys' goalless friendly against Slavia Prague earlier this week.
Initial reports suggested that Boyata would miss around six weeks of action, ruling him out of Celtic's upcoming Champions League qualifiers, but the damage is more severe than first thought.
Speaking to reporters on Friday afternoon, Celtic assistant Chris Davies said: "Unfortunately for Dedryck, it looks like he is going out to be out for a few months with a medial knee ligament injury.
"It's really disappointing for Dedryck. He did really well for us for the last six months of last season and was in good form. We are all disappointed for him, but no doubt he will do the work he has to do in rehab and come back even stronger and better.
"The timeline that the medical team are looking at is up to three months but we are always optimistic and we will see what we can do."
Boyata started 21 games for Celtic last season as they cantered to the Scottish Premiership title, while also winning both domestic cups.