Fiorentina defender Micah Richards must undergo tests to establish the extent of the thigh injury he picked up in midweek.
The Manchester City loanee contracted the problem during his side's 3-0 win over Dinamo Minsk in Group K of the Europa League, forcing him off before half time.
Fiorentina are yet to confirm how long Richards is likely to be sidelined for, but the initial prognosis is believed to be three weeks.
"During [the] Europa League match, Micah Richards reported discomfort in the flexor tendons of his right thigh," read a statement on the club's website. "The injury forced him out of the clash before half time. He will undergo tests tomorrow."
Richards has made four appearances for Fiorentina since joining the club on a season-long loan during the summer transfer window.