Celta Vigo were beaten for the fifth time in six La Liga games, going down 3-0 at home to Athletic Bilbao on Sunday with the Galicians distracted by Thursday's Europa League semi-final against Manchester United.
Eduardo Berizzo made nine changes from the side that started Thursday's 2-1 defeat at Sevilla and Athletic's greater desire for the points showed as they boosted their bid to qualify for next season's Europa League.
Raul Garcia struck either side of half-time before Mikel Rico wrapped up a vital three points for the visitors to take them above Basque rivals Real Sociedad into sixth.
Elsewhere, Leganes failed to take a step closer to survival as they were beaten 2-0 at Eibar.
Alaves came from a goal down to thrash Real Betis 4-1.
And Deportivo la Coruna moved eight points clear of the relegation zone with just three games remaining thanks to a 2-2 draw at already relegated Osasuna.