Manchester City are reportedly concerned that Benjamin Mendy's knee injury could keep the defender out of action for a significant spell.
The 23-year-old suffered the blow following a challenge from Andros Townsend in Saturday's 5-0 win over Crystal Palace.
According to the Daily Mail, Mendy will travel to Barcelona to see knee specialist Ramon Cugat and undergo further tests after an initial scan came back inconclusive.
It is believed that City will learn by the end of the week whether the Frenchman, who joined the club from Monaco in the summer for £52m, has suffered ligament damage.
Mendy has made five appearances so far this season.