Celtic manager Neil Lennon has confirmed that Scott Brown will be out of action while the club assess his persistent ankle injury.
The problem surfaced again in Sunday's 4-2 Old Firm defeat to arch rivals Rangers at Ibrox leading to his withdrawal on 74 minutes.
The midfield talisman has only just returned to Lennon's starting XI after missing the last two games due to injury.
Lennon is unsure how long Brown will be unavailable, but he knows they need to think long-term in order to boost his availability.
"The ankle has gone again unfortunately," bemoaned Lennon.
"He felt fine before the game, he trained the day before the match and looked great for an hour.
"He actually got us playing in the first half and was instrumental in both our goals so it was a blow losing him.
"We don't know how long he is going to be out for now.
"It looks as if he is going to be shut down for a while until we can let it settle and get it right."