Ousmane Dembele is expected to miss a run of important games for Barcelona after suffering a strained thigh in their LaLiga win over Girona on Saturday.
The French winger, described by coach Xavi as Barcelona's "most important player in one-on-one situations", may struggle to be back in time for the Europa League play-off first leg against Manchester United, which takes place on February 16 at Camp Nou.
Barcelona have yet to give an official estimate of how long Dembele faces on the sidelines, but local reports have suggested it may be a three-week absence.
The injury took some of the shine off an eighth win in nine LaLiga games, in which Dembele's replacement off the bench, Pedri, scored the only goal.
Dembele made way after 26 minutes and underwent checks before visitors Barcelona embarked on their short journey home.
Barcelona announced on their website: "Tests this evening on Ousmane Dembele have revealed that he has strained the rectus femoris muscle in his left thigh. It means he is sidelined until he can recover from the injury."
Xavi said of Dembele's blow: "It's a shame because he is an important player."
Dembele has eight goals and seven assists for Barcelona this season, with those combined 15 goal involvements bettered only by Robert Lewandowski's 27 (22 goals, five assists) among Xavi's squad.
Barcelona have LaLiga games against Real Betis, Sevilla and Villarreal before the United game.