Barcelona were handed their first defeat of the season by Atletico Madrid on Sunday.
Diego Forlan's clinical finish and a superb Simao Sabrosa free-kick fired Atletico Madrid to a 2-1 home win over previously unbeaten La Liga leaders Barcelona on Sunday.
Second-placed Real Madrid's 3-0 win at bottom club Xerez on Saturday had trimmed Barca's lead at the top to two points and Pep Guardiola's side, missing five first-team defenders through suspension or injury, failed to respond.
With 22 matches played, Barca have 55 points, Real 53 and Valencia, who were held 1-1 at mid-table Sporting Gijon on Saturday, are third on 43. Erratic Atletico, who are through to the King's Cup final, are 11th with 27.
Jose Antonio Reyes played Forlan through to score Atletico's first in the ninth minute and the home side doubled their lead in the 23nd when Simao arrowed a free-kick past Barca goalkeeper Victor Valdes.
Zlatan Ibrahimovic pulled a goal back for the visitors four minutes later when he was left unmarked at the back post at a corner and volleyed high into the net from close range.
The Swedish striker was twice denied by well-timed challenges from defender Luis Perea at the start of the second half and Valdes did well to keep out a fierce drive from striker Sergio Aguero.
Earlier on Sunday, Deportivo Coruna lost 2-0 at Espanyol and missed another opportunity to break into La Liga's top four.
The Galicians fell behind when Joan Verdu netted at the near post just before the break and their cause was further hindered when midfielder Antonio Tomas was sent off for elbowing just after the restart.
Jose Callejon's curling effort sealed victory for 11th-placed Espanyol and left Depor occupying sixth spot with 35 points from 22 matches.
Fourth-placed Real Mallorca (37 points) visit struggling Tenerife in the newly-reinstated Monday night game.