Manchester City boss Manuel Pellegrini is extremely worried about number one goalkeeper Joe Hart, who limped off the field during their 1-0 Champions League defeat to Juventus, according to reports from the Mirror.
Mario Mandzukic scored the only goal of the night to put the Serie A champions top of the group.
But with just eight minutes left in the fixture, Hart was forced off with a suspected hamstring problem after a save to deny Alvaro Morata.
The England international is set to undergo tests in order to assess the extent of his injury, but Pellegrini revealed he has total trust in reserve goalkeeper Willy Caballero.
Pellegrini said: “It is impossible to know how serious Hart’s injury is. He has a problem with his hamstring. He has been carrying a problem in his back for the week.
“We hope not to lose him. But for if for some reason he cannot play I have trust in Willy (Caballero).”
Despite both teams already qualifying for the knock-out phase, the loss to Juve sees City needing to beat Borussia Mochengladbach and Juventus to lose to Sevilla to have any chance of qualifying as the top team from the group.
The Citizens have now lost two games in succession after their 4-1 thrashing by Liverpool during the weekend, and will hope to turn their form around when Southampton visit the Etihad on Saturday.