Rangers manager Steven Gerrard has revealed defender Filip Helander has undergone surgery on a knee injury and will be missing "for the foreseeable future".
Helander suffered the injury in Saturday's 2-1 win over St Johnstone and required a stretcher to leave the pitch at McDiarmid Park.
The 28-year-old will now miss Thursday's Europa League match against Lyon at Ibrox and Gerrard says it will be "at least a few months" before the defender returns.
"Helander will be missing," Gerrard said at his pre-match news conference.
"He has had surgery in the last 24-48 hours to fix an issue that they spotted when they went inside to have a look so he will be missing for the foreseeable future.
"The rest is as it was so we are in good health besides Fil."
Gerrard added: "I've not had a chance to speak to Fil post-surgery but I will do as soon as possible to see how he is mentally and physically.
"It is difficult to put a time on his return for now but will be at least a few months."
Connor Goldson missed the win over St Johnstone after he was forced to self-isolate because of coronavirus protocols.
The 28-year-old has now been cleared to face Lyon and is likely to partner Leon Balogun in central defence.
"Connor Goldson comes back and is available for tomorrow," added Gerrard.
"I am confident we have cover and will manage despite being disappointed Filip is missing."
Lyon eased to a 3-1 win against Strasbourg at the weekend with former Celtic stars Moussa Dembele and Jason Denayer both on target.
Peter Bosz's side have an important week - after playing in Glasgow, they travel to face Lionel Messi, Neymar and Kylian Mbappe on Sunday in a Ligue 1 clash with PSG.
Gerrard is wary of the quality of the French side but has challenged his players to be "brave" in front of their home support.
"At full strength, Lyon are very much a Champions League team with Champions League-calibre players, they have a manager who got this job on the back of doing ever so well as the Bayer Leverkusen manager," added Gerrard.
"He has been here before, he knows what we are about so this is a real big test tomorrow and there is no doubt about it we have to be at our best and that goes for both sides of the game.
"We have to have a high level of focus and concentration tomorrow because if you don't against these teams you can be punished and punished very quickly so it is a real good test and challenge.
"But we have to have our own confidence and belief that we can play at this level, we can compete and at the right times during the game, we have to show bravery that we can hurt the opposition as well.
"We are excited, we are looking forward to it but we know the size of the challenge and it is arguably the biggest we have had as a group."