Hakan Calhanoglu could miss Inter Milan's Champions League quarter-final with Benfica next month after the Serie A club said on Thursday the Turkey midfielder had suffered a thigh injury.
In a statement, Inter said tests near Milan revealed Calhanoglu had pulled a muscle in his right thigh and that "his condition would be reassessed in the coming days".
Calhanoglu was substituted in the first half of Turkey's 2-0 Euro 2024 qualifying defeat to Croatia on Tuesday.
Inter, who sit third in Serie A, did not say for how long the 29-year-old would be out of action but Italian media report that he will be sidelined for a month.
It would rule him out of a key period for his club.
They face Benfica over two legs, on April 11 and eight days later, after taking on fierce rivals Juventus in the Italian Cup last four.
Inter are also in a battle to stay in Serie A's Champions League positions.
Calhanoglu has played 35 times for Inter in all competitions, scoring three goals.
