Real Madrid centre back Antonio Rudiger has injured a muscle in his left leg with reports on Friday suggesting he could be sidelined for around two months.
Rudiger, 32, suffered the injury in training on Friday and will have more tests in the next few days, but the AS daily reported that the injury was "serious".
Real said in a statement that scans had shown Rudiger had "an injury to his rectus femoris muscle" but made no mention of how long he would be out.
The veteran German international has made a single LaLiga appearance this season.
He battled through injury last season, but still made 55 appearances for the club.
Real Madrid signed an additional centre-back this summer, taking the 20-year-old Netherlands-born Spanish international Dean Huijsen from Bournemouth.
But the Spanish giants are said to be keen to sign France international centre-back Ibrahima Konate from Premier League champions Liverpool, possibly at the end of this season.
Real face Real Sociedad away in LaLiga on Saturday, and the 13-time European champions begin their Champions League campaign at home to Marseille on Tuesday.