Fourth-placed Villarreal kept up the pressure on Valencia with a hard-fought 1-0 win at home over Real Zaragoza on Monday.
The result cut third-placed Valencia's buffer over Villareal to six points with six games remaining as the two sides chase the third and final automatic Champions League place in La Liga.
A fourth-placed finish would see that side be forced into the qualifying play-offs for Europe's richest club competition.
American-born Italian international Guiseppe Rossi scored the decisive goal of the match from the penalty spot with 20 minutes to play after he was upended by a crude challenge from Argentine midfielder Leonardo Ponzio.
The match itself was a spiteful affair, which saw seven players booked and Real Zaragoza's Nigerian striker Ikechukwu Uche sent off for a second caution in the fourth minute of stoppage time, when referee Javier Turienzo Alvarez booked him for diving.
The loss leaves Zaragoza in 17th place, with only goal difference separating them from the relegation zone.