Barcelona midfielder Sergio Busquets is a doubt for his side's Champions League last-16 second leg against Manchester City on March 18.
Busquets, 26, was carried off on a stretcher in Wednesday's 3-1 Copa del Rey semifinal second-leg win at Villarreal after hurting his right ankle.
Barca confirmed following the game that the Spain international had injured ligaments, before giving a further update a day later after the player had undergone tests.
"Tests done on Thursday morning confirmed that Busquets has a right ankle syndesmosis injury," a Barcelona statement read.
Busquets out of Rayo game http://t.co/5JbEMghsPg pic.twitter.com/4vUBscaxY9
- FC Barcelona (@FCBarcelona) March 5, 2015
"The player is ruled out for Sunday's league match with Rayo Vallecano at the Camp Nou. His availability beyond that will be carefully monitored."
Busquets, who last week extended his contract with Barca until June 2019, is expected to also sit out the Primera Division game at Eibar on March 14.
However, Blaugrana coach Luis Enrique will be hoping to have the midfielder available four days later when his side -- who hold a 2-1 advantage from the first leg -- host City in the Champions League.
Busquets should, though, definitely be fit in time for the clasico against Real Madrid in La Liga on March 22.