Manchester City loanee Daniel Arzani has suffered a blow after being ruled out of the whole season.
The Australian youngster will now undergo tests and surgery.
"I received the bad news today that I will indeed need an ACL (anterior cruciate ligament) Op ruling me out until next season," he wrote on Instagram.
"Apologies to the Celtic fans for my 20-minute cameo. This is, however, the beginning of my journey and I promise to be back better than ever. Day 1 road to recovery starts now."
The 19-year-old had been in the Australia fold as well - prior to his injury.