Barcelona cruised to victory as Robert Lewandowski scored a second-half hat-trick after Valencia goalkeeper Giorgi Mamardashvili was sent off.
The hosts, who are on the cusp of relinquishing the La Liga title to Real Madrid despite the victory, took the lead when Fermin Lopez struck.
But they had Mamardashvili sent off just before half-time and the 35-year-old Poland striker took full advantage.
Lewandowski equalised early in the second half with a header then nodded in a rebound before getting his third from a free-kick in added time.
Barcelona remain second in La Liga, 11 points behind Real Madrid with five games remaining.
Valencia stay eighth and face a battle to qualify for Europe next season as they lie four points behind sixth-place Real Sociedad.
