Ibrahim Diabate scored the decisive first-half goal as FC Barcelona, the reigning La Liga champions, slipped to a surprising 1-0 defeat against relegation-threatened Deportivo Alavés at the Estadio de Mendizorroza.
Having already secured back-to-back league titles with a win over arch-rivals Real Madrid at the Camp Nou on Sunday, Barcelona began the final stretch of their season but were quickly brought back down to earth in Vitoria.
FC Barcelona head coach Hansi Flick saw his side fall behind right at the end of the first half when Antonio Blanco nodded a corner back into the danger area and Diabate reacted fastest, prodding the ball beyond Wojciech Szczesny.
The hosts, fighting for survival, had started brightly with Diabate testing Barcelona early on, while the champions responded with spells of control and several half-chances through Roony Bardghji, Jules Koundé, Marcus Rashford, and Dani Olmo, none of which could break the deadlock.
Alavés grew into the contest as Abde Rebbach and Toni Martínez both threatened, while Nahuel Tenaglia also forced a routine save, but it was the home side who struck the decisive blow just before the interval.
After the restart, Barcelona pushed for an equaliser, introducing Ferran Torres, Pedri, Xavi Espart, and Marc Bernal in a triple substitution aimed at changing the flow of the game.
However, Antonio Sivera remained firm in goal as he dealt with repeated deliveries and late efforts.
Alavés came close to doubling their lead when Jon Guridi struck the woodwork, though the effort was ruled out for offside, and they continued to defend resolutely under pressure.
In the closing stages, Rashford created one final opening with a clever flick into Olmo, only for Sivera to smother the attempt, before the English forward also failed to convert a cross from João Cancelo.
Despite late pressure, Alavés held firm through a nervy finish to claim a vital three points that lifted them out of the relegation zone, while Barcelona’s 11-game league winning streak came to an end with two matches remaining in their season against Real Betis and Valencia.
