Athletic Bilbao's top-four finish ambitions were dented in a narrow 1-0 defeat by Valencia on Saturday in La Liga.
Valencia triumphed over their third-place visitors in an even battle, with Hugo Duro's header splitting the sides at their Mestalla stadium.
Ernesto Valverde's Athletic were unbeaten in 14 matches across all competitions and had won their previous six.
However, they came up against another in-form side in Ruben Baraja's sturdy Valencia, who ground out their fourth consecutive La Liga victory to move seventh.
"The worst thing is we had control of the game, we got up there well but didn't make many dangerous chances," said Valverde.
Sergi Canos went off injured for the hosts early on, while Valencia goalkeeper Giorgi Mamardashvili made two saves from Nico Williams.