Barcelona expect Ansu Fati to be out for four months after the club confirmed the 18-year-old underwent surgery on his knee injury on Monday.
Fati had the operation after tearing the internal meniscus of his left knee during Barca's 5-2 win over Real Betis on Saturday.
He will miss the majority of the rest of the season but could return for the run-in and will hope to be fit again in time to play for Spain in next summer's European Championship.
Barca's chances in La Liga and the Champions League have been dealt a blow by Fati's injury, given the forward had emerged as one of Ronald Koeman's most exciting players.
Fati has already scored five goals and provided two assists in his 10 appearances this term.
"Ansu Fati has been operated on successfully by Dr. Ramon Cugat for the injury to the internal meniscus of his left knee under the supervision of the Club's medical staff. The player will be out for approximately four months," Barcelona said in a statement.
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)