Barcelona are awaiting scan results on star midfielder Pedri after he sustained a hamstring injury against Eintracht Frankfurt on Thursday.
The Blaugrana prospect was replaced by Frenkie de Jong at half-time against the Bundesliga side, who progressed to the Europa League semi-final with a dramatic 4-3 aggregate victory.
Pedri was struggling with a problem in his left thigh, and Barca coach Xavi acknowledged he was worried by the injury, adding: "It's very bad news."
Further scans on Friday were undertaken to determine the extent of the issue for Pedri, who was sidelined for an extended period earlier this year with another hamstring problem.
The news of the injury to the midfielder will further compound the disappointment of Barca's exit from the Europa League.
Pedri has played only 12 matches in La Liga this season, starting 10. Barca have won eight of those 10, compared to nine victories in 20 without the teenager.
The midfielder scored in his most recent La Liga appearance, a 3-2 win over Levante on Sunday, his third goal in five matches at the time. He had scored only three times in his prior 46 appearances.
Xavi will have to make do without Pedri when his side host Cadiz on Monday as they look to cut leaders Real Madrid's 12-point lead.