Antonio Puerta, Javier Chevanton and Jose Luis Marti scored second-half goals Sunday to help Sevilla beat Espanyol 3-1 and boost its chances of a first Spanish league title since 1946.
Sevilla moved two points ahead of FC Barcelona, which will reclaim the leadership if it beats Levante in Sunday's late game.
Sevilla has 61 points and defending champion Barcelona has 59. Real Madrid, which visits Athletic Bilbao later Sunday, has 57. Valencia has 56, two more than Zaragoza.
Sevilla couldn't get past Espanyol goalkeeper Carlos Kameni in the first-half of a matchup which could be repeated in next month's UEFA Cup final.
However, midfielder Puerta seized on a loose ball to give Sevilla the lead in the 51st, with striker Chevanton shooting the second goal in the 53rd while lying on the ground.
Ferran "Coro" Corominas, who scored in Espanyol's 3-0 win over Werder Bremen in the first leg of the UEFA Cup semifinals last Thursday, reduced the deficit when he beat Sevilla's offside trap in the 60th.
Playing with a host of reserve players, Espanyol conceded a third goal in the 74th minute when substitute Marti angled a low shot from the edge of the penalty area.
Also, Zaragoza failed to climb into fourth place when it drew 2-2 at Osasuna.
Juanlu Gomez opened the scoring for the UEFA Cup semifinalist in the fifth minute, with Zaragoza midfielder Pablo Aimar equalizing direct from a free kick in the 12th.
Valdo Lopes restored Osasuna's lead in the 55th, with Sergio Garcia leveling in injury time.
Also Sunday, it was: Racing Santander 0, Deportivo La Coruna 0; Getafe 1, Real Sociedad 0; Gimnastic Tarragona 0, Villarreal 3; and Celta Vigo 0, Mallorca 3.
Santander missed the chance to climb into seventh place by playing out a stalemate with Deportivo.
Sociedad's bid for its third straight win foundered at Getafe, leaving the 19th-place club in increased danger of relegation.
Defender Alexis Ruano headed the winning goal in the 71st minute.
Tarragona looks doomed to relegation following a heavy defeat against Villarreal.
Diego Forlan scored his 11th and 12th goals of the season in the 18th and 79th minutes, with Matias Fernandez adding Villarreal's third in injury time.
Celta also increased its relegation worries after crashing at home to Mallorca.
Early long-range goals by Juan Arango and Fernando Varela and a late strike by substitute Maxi Lopez brought Celta coach Hristo Stoitchkov his second defeat in three games since taking charge earlier this month.
On Saturday, Valencia beat Recreativo Huelva 2-0, while Atletico Madrid drew 0-0 with Real Betis.