Villarreal climbed to third place in the Primera Liga with a battling 1-0 win over Athletic Bilbao at San Mames.
The Yellow Submarine put their recent indifferent domestic form behind them with a valuable three-point haul against their fellow European hopefuls.
Although they have tasted success in the Europa League recently, beating Bayer Leverkusen home and away to reach the quarter-finals, Villarreal had won just one of their previous seven league matches, but they were victorious again thanks to Marco Ruben's second-half header.
The victory means the Yellow Submarine move level on 54 points with Valencia, who suffered a 1-0 reverse at home to Sevilla in the day's late kick-off.
Ivan Rakitic scored the only goal midway through the second half, slamming home a loose ball to put his side to within 12 points of Valencia, who drop to fourth.
Osasuna took a huge step towards survival as they thrashed struggling Hercules 4-0 in Alicante to move into the top half of the table. The result would cost Esteban Vigo, the Hercules coach, his job.
Goals from Javier Camunas and Nelson saw the Pamplona-based side go two up before the break, before second-half strikes from Krisztian Vadocz and Kike Sola sealed an emphatic victory.
Sporting Gijon gave their hopes of surviving the drop a further boost whilst damaging Almeria's own chances after claiming a narrow 1-0 win in a clash between the two relegation rivals.
Miguel De Las Cuevas' hotly-disputed early strike proved the difference as Sporting, who started the match one spot and three points above 18th-placed Almeria, continued their recent revival.
Salomon Rondon hit both goals as Malaga boosted their chances of survival with a precious 2-0 win at home to Espanyol.
On-loan forward Giovani dos Santos struck a second-half winner in a 2-1 victory against Real Sociedad to help Racing Santander ease themselves away from relegation trouble.
After a first half littered with shots from distance, Santander took the lead with a spectacular opener from Kennedy Bakircioglu. Antoine Griezmann brought Sociedad level after the break, before Tottenham forward Giovani settled matters.
Finally, a late Ruben free-kick earned Levante a 1-0 win against Deportivo La Coruna at the Estadio Riazor and maintained the Valencia club's impressive recent run of form.