Manchester City midfielder Kevin De Bruyne appeared to suffer a problem in the closing moments of the first half against Inter Milan and did not appear for the second, with Phil Foden taking his place.
The Belgian has suffered a number of muscle injuries in recent years and was subbed off during last year's Champions League final against Inter.
He also missed a chunk of last season after yet another muscle injury.
Guardiola offers De Bruyne update
Speaking after the game, City boss Pep Guardiola said he had no idea what the situation was.
🚨🇧🇪 Pep Guardiola on Kevin de Bruyne subbed off at half time: “I’ll have more info on his conditions on Thursday”.
— Fabrizio Romano (@FabrizioRomano) September 18, 2024
“Back to face Arsenal? We’ll see from tomorrow”. pic.twitter.com/4DQH5Ojhrg
"I didn't speak with the doctors yet. I will have more info tomorrow," he said.
"The way Inter defended, I was thinking after 35 minutes that I wanted to make this substitution.
"After the doctor said to me that Kevin was not ready to play but I was ready to make this substitution anyway."
The champions will hope their talisman is back and ready for the big game against Arsenal this weekend but Phil Foden's lively return to action will also please the fans and the manager.