Sevilla knocked Barcelona off the top of the Primera Liga after goals from Frederic Kanoute and Adriano Correia earned a 2-0 home win over Osasuna on Sunday.
The UEFA Cup holders have 21 points, one ahead of Barca who were held to a 1-1 draw at Deportivo Coruna on Saturday.
Real Zaragoza climbed to third on 19 points with a 3-1 home win over Getafe, and Real Madrid slipped to fourth on 17 after losing 2-1 at home to Celta Vigo.
Sevilla were set on course for a fifth straight home league win when Mali striker Kanoute scored from the penalty spot early in the second half, taking his tally for the season to eight.
Two minutes from time Kanoute fed Brazilian midfielder Adriano to finish a swift counter-attack and wrap up the win.
"It's a nice position to be in for the fans and for the club, but we have only played nine games and the season is very long. We must maintain this level of work," said Sevilla coach Juande Ramos.
Zaragoza moved within two points of the leaders with their victory over 10-man Getafe.
Bernd Schuster's side lost defender Ruben Pulido to a red card after just 11 minutes but managed to level from the penalty spot after Uruguayan Carlos Diogo had put Zaragoza in front.
But second-half strikes from Argentine Diego Milito and Brazilian Ewerthon sealed the win for Zaragoza. Milito's goal kept him joint-top scorer in the league with Kanoute.
Below them Real Madrid failed to capitalise on Barca's slip up as Fabio Capello suffered his first defeat at the Bernabeu in two spells as coach of the nine-times European champions.
Capello gave unsettled Ronaldo his first start of the season but it was Celta, who were content to cede possession and play on the break, who struck first.
Brazilian striker Nene put the visitors in front after 36 minutes with their first effort on target, but Real levelled just before the break when Brazilian midfielder Emerson headed home from Raul's corner.
Capello experimented with Ronaldo and Dutch striker Ruud van Nistelrooy up front after the break but, after Nene curled a shot against the bar, he sought to reinforce his midfield again bringing on David Beckham for the Brazilian.
As the game opened up Celta keeper Jose Manuel Pinto kept the away side in the match and eight minutes from time the visitors pounced on a stray pass from Jose Antonio Reyes.
Angel's cross to the edge of the area was swept inside the far post by former Atletico Madrid midfielder Jorge for the winner.
Injury-hit Valencia have lost their fluidity and could only draw 1-1 at lowly Espanyol, who played most of the second half with 10 men.
Espanyol's Albert Riera put the Catalans ahead but, after David Silva equalised just before the break, he was harshly sent off.
Valencia are level with Real on 17 points but fifth on goal difference, a point ahead of Getafe and two clear of Deportivo and Villarreal, who came from behind to beat Real Betis 3-2.