Celtic head to Seville for a vital Europa League clash against Real Betis without talismanic captain Callum McGregor.
Ange Postecoglou confirmed that the influential midfielder picked up a knock in training but no timescale was provided over his return.
The 28-year-old has played an insane amount of games over the last five seasons and his absence is a major blow to Celtic ahead of their trip to Spain.
Only James Forrest has made more appearances in green and white than McGregor in the current squad, and with the winger still recovering from injury, Postecoglou faces a dilemma over who wears the armband on Thursday night.
There's been a huge turnover in Celtic's squad this summer and with no outstanding captaincy candidate, we assess three players who could lead the Glasgow giants out at Estadio Benito Villamarín.
Joe Hart
The experienced goalkeeper is most likely to captain Celtic in McGregor's absence.
Despite only arriving in the summer, the former England number one has played at the highest level and has already demonstrated his leadership abilities at Celtic.
Hart has played on the biggest stages for club and country. He's represented England at the World Cup and European Championships while playing for Manchester City in the Champions League.
The 34-year-old is extremely vocal and he's already established himself as a huge presence in the Celtic dressing room.
He took the armband after McGregor went off at the weekend and looks most likely to do so again.
Tom Rogic
Although not guaranteed to start, Rogic will have the most Celtic appearances to his name from the starting eleven if he gets the nod.
The Australian isn't your conventional leader but he's highly-valued by his countryman Postecoglou and a respected member of the squad.
Rogic is coolness personified on the pitch and Postecoglou will want his players to emulate that calmness in a red-hot Europa League atmosphere.
The 28-year-old isn't the most vocal figure but he's an outside bet to be handed the armband.
Albian Ajeti
The Swiss striker was handed the captaincy for Postecoglou's first game in charge against Sheffield United.
Celtic named a young squad for that pre-season friendly but it was still a slight surprise that Ajeti was handed the armband.
The 24-year-old would be unlikely to feature if Kyogo Furuhashi or Georgios Giakoumakis were fit and it's unlikely that he will be named captain tomorrow night.
James McCarthy would be a strong candidate given his experience at international level and in the English Premier League but his selection isn't guaranteed.
Ajeti struck twice for Celtic at the weekend however and if he does start, he is in with a chance of continuing his renaissance by taking the armband.
