Barcelona defender Xavi Espart will miss "around seven weeks" with an ankle injury, the LaLiga leaders said on Monday.
The 19-year-old full-back was taken off hurt during the 2-1 Clasico defeat by Real Madrid on Sunday at Camp Nou.
Espart broke into the team this season and had become a regular starter for Hansi Flick.
The defender joins several teammates on the sidelines, including Jules Kounde, Eric Garcia, Andreas Christensen and Dani Olmo.
Espart will miss the trip to Atletico Madrid in LaLiga on November 8, along with Champions League matches against Aston Villa, Sabah and Manchester City, among other games.
After their first domestic defeat of the campaign, Barcelona lead the top flight by two points from Atletico and are three ahead of Jose Mourinho's Real Madrid.