Barcelona's title ambitions were dealt a further blow as they were beaten 2-1 at home by Valencia, suffering a third consecutive league defeat for the first time since 2003.
An own goal by Ivan Rakitic gave Valencia a shock lead on 27 minutes and Santi Mina doubled their advantage just before the break.
Lionel Messi scored his 500th career goal for club and country to reduce the deficit midway through the second half, but was unable to inspire a comeback.
Barca remain top of the Primera Division on 76 points but are only ahead of Atletico Madrid due to their superior head-to-head record. Just three weeks ago they led Diego Simeone's side at the top by nine points.
Sunday's result means Barca have now picked up just one point from their last four league games and, if that was not bad enough, they were also knocked out of the Champions League quarterfinals by Atletico in midweek.
Atletico Madrid built on their Champions League success over Barcelona by beating Granada 3-0.
Koke opened the scoring in the 15th minute and in the second half teed up Fernando Torres to score for the fourth game in a row to put the hosts further at ease, while substitute Angel Correa grabbed the third late on.
Diego Simeone's side remain hot on Barca's heels after a third successive league win, while Granada are just one point above the relegation zone.
Athletic Bilbao eased the pain of their cruel penalty shootout elimination from the Europa League by beating Malaga 1-0 to boost their hopes of qualifying for the competition again next season.
Raul Garcia's header in the 53rd minute gave the visitors the lead against the run of play but they held on for the three points thanks to some fine saves from goalkeeper Gorka Iraizoz.
Athletic capitalised on Celta Vigo drawing with Real Betis to move ahead of the Galicians and up to fifth in the Primera Division, while Malaga stay eighth.
Sevilla failed to win at home for a second successive time as substitute Oriol Riera's late strike saw them held to a 1-1 draw by Deportivo La Coruna.
Riera converted in the 81st minute from Lucas' tee-up, cancelling out Vicente Iborra's 21st-minute header.
Sevilla, who booked their place in the Europa League semifinals on Thursday, had won 13 home league games in a row before losing 2-1 to Real Sociedad at the Ramon Sanchez Pizjuan Stadium earlier this month.
Rayo Vallecano moved five points clear of the relegation zone after a fine Miku header sealed a 2-1 home victory over Villarreal.
Miku showed great technique in the 81st minute as he diverted the ball in from Tito's cross.
The 16th-placed hosts had initially gone in front in the seventh minute via Javi Guerra's close-range effort, with Villarreal -- who look destined to finish in their current position of fourth -- subsequently pulling level through a Adrian's delightful 20th-minute finish.