Barcelona fell behind to Real Oviedo at the Estadio Carlos Tartiere after a costly error from goalkeeper Joan Garcia.
Hansi Flick’s side had created chances in the first half, with Marcus Rashford twice denied by Aaron Escandell and Raphinha striking the post. But their failure to take the lead proved costly when Oviedo struck first.
Garcia miscontrolled a ball outside his box and misplaced a pass, allowing Alberto Reina to fire into the net from 35 yards. The spectacular strike delighted the home crowd and left Barcelona chasing the game.
The goalkeeper’s decision to join Barcelona from Espanyol this summer had already drawn attention, though his early season form had been widely praised. He was key in earning a draw against Rayo Vallecano on matchday three, but now faces criticism for his error.
Barcelona risk falling five points behind Real Madrid if they lose the match, with Flick’s side under pressure to find an equaliser to stay in the La Liga title race.