Defender Carl Starfelt has revealed he will miss a minimum of two weeks - keeping him out of Celtic's crucial clash with Ferencvaros.
Ange Postecoglou 's side travel to Hungary on Thursday knowing that they must take all three points to keep their Europa League knockout stage hopes alive.
After the Swede limped off against Livingston with a hamstring injury, the Australian will have to mastermind the win without his first-choice centre-back.
The defender has confirmed to outlets in his homeland that he will miss the European showdown and then the trip to Dundee on Sunday.
Following that, he will have the international break after that to allow him time to recover.
He told Fotbollskanalen : "I have an X-ray tomorrow (Monday) so we will have to look out for it (results), but it's probably an easier stretch. That is still a couple of weeks"
Having emerged as a stand-out performer at the back for Celtic after a stuttering start to life in Glasgow's east end, Postecoglou will have to dig into his squad to replace the defender.
Stephen Welsh looks like the obvious choice to parter Cameron Carter-Vickers, but the 21-year-old hasn't been given game time since the 1-0 defeat to Livingston.
Nir Bitton could also drop into the centre-back role to plug the gap at the back.
Forgotten summer signing Osaze Urhoghide or youngster Dane Murray could also be drafted in for the crucial fixture.
