Eden Hazard will miss the first leg of Real Madrid's Champions League last-16 tie against Manchester City after breaking his ankle.
The 29-year-old limped off during Saturday's 1-0 defeat against Levante.
It was only his second match since returning from another ankle injury which had kept him out of action for almost three months.
Real Madrid assessed the injury overnight and confirmed on Sunday that Hazard had suffered a fracture. They have been unable to put a time frame on his period of recovery.
A club statement said: "Following the tests carried out on our player, Eden Hazard, by the Real Madrid medical department, he has been diagnosed with a fracture to his right distal fibula."
Real's first defeat in the league since October saw them fall to second place in La Liga on 53 points after 25 games.
Barcelona replaced them at the top of the table on 55 points after beating Eibar 5-0 earlier in the day.