Espart was replaced by Alejandro Balde in the 30th minute. Barca say collision with Real player caused injury.
Espart, 19, has played nine games for the Catalan club this season, with two goals and two assists. Barcelona are already without defenders Andreas Christensen, Jules Kounde and Eric Garcia due to injury.
Joao Cancelo, Balde, Pau Cubarsi and Gerard Martin are the only available defenders in the squad. Injury timeline means Espart may not play again in 2026, with Barca's final game this year set for December 20.