Real Sociedad’s 19-game unbeaten run was bought to an end by a 3-0 away defeat to 12th placed Athletic Bilbao.
The Primera Division leaders also saw their lead at the top of the table cut to just four points as Real scraped a draw at Espanyol.
Bilbao’s first goal came on 18 minutes from former Sociedad player Joseba Etxebarria. Etxebarria scored again with 15 minutes left to double their lead. Sociedad’s situation went from bad to worse when Nihat Kahveci was sent off for a foul on Bittor Alkiza. Santiago Ezquerro scored a third in stoppage time.
Second placed Real Madrid failed to make up much ground on the leaders as they only managed a 2-2 draw against 17th placed Espanyol.
Real Madrid were forced to come back from two goals down after conceding first half efforts to Roger and Raul Tamudo.
Madrid drew level thanks to long range goals from Roberto Carlos and Luis Figo.
The crisis at Barcelona deepened as they lost 3-0 to Athletico Madrid. New Barcelona manager Radomir Antic watched as Barcelona lost their third game on the trot and dropped to within three points of the relegation zone.
Both teams were reduced to ten men on the 64th minute when Jose Mari and Fabio Rochemback were dismissed for clashing off the ball.
After the game Antic said he needed: “total dedication” to save Barcelona from relegation.
Third placed Valencia took advantage of the top two’s slip by claiming victory over Mallorca. The only goal of the 1-0 victory was scored by Mista on 79 minutes. The victory means Valencia are now within 5 points of the leaders Real Sociedad.
Deportivo La Coruna secured a 2-0 win over fellow contenders for the final champions league spot, Real Betis. Roy Makaay and Diego Tristan scored for fourth placed Deportivo.
At the other end of the table bottom placed Recreativo de Huelva slumped five points adrift after losing 4-0 to Malaga.
Second-from-bottom Rayo Vallecano managed a 1-1 draw against Alaves, and gained 1 point on 18th placed Racing Santander who lost 2-1 to Valladolid.
Elsewhere 14th placed Villareal beat Osasuna 1-0 and 11th placed Sevilla beat Celta Vigo 1-0.