Barcelona forward Dani Olmo (26) has been sidelined for up to five weeks after injuring his right hamstring, the LaLiga club said on Monday.
He appeared to suffer muscle discomfort after scoring in Sunday's 4-1 league win at Girona and was substituted in the 61st minute.
Olmo's injury is a blow to manager Hansi Flick's side as they begin their European Champions League campaign on Thursday, coming off a perfect start to their domestic league campaign so far.
The Spain international, who joined from RB Leipzig for 55 million euros ($61 million), has scored in all three of his appearances for Barca.
The Catalan club face AS Monaco at the Stade Louis II on Thursday before Sunday's LaLiga trip to Villarreal.