Barcelona closed the gap with leaders Real Madrid after a late Ronaldinho penalty earned them a 2-1 victory over Zaragoza on Saturday.
Real Madrid slipped to their second defeat in three games after surrendering an early lead to lose 2-1 at struggling Real Betis. The Galacticos now have a narrow five-point lead at the top.
The Brazilian midfielder converted in the 83rd minute, moments after Zaragoza defender Juan Francisco Garcia received a yellow card for a dubious hand ball inside the area.
Barcelona improved to 51 points, while Madrid fell to a lightly regarded team for the second time in three weeks.
Real Madrid midfielder Royston Drenthe put the Primera Liga pacesetters in front in the sixth minute but Betis struck two quickfire goals before the break, Brazilian forward Edu heading the first and winger Mark Gonzalez nodding the second.
Improving Sevilla moved up to sixth with a 4-2 victory in an entertaining match at Espanyol.
Brazil striker Luis Fabiano took his tally for the season to 17 when he fired Sevilla's opening goal while African Footballer of the Year Frederic Kanoute added the second.
Christian Poulsen and Diego Capel were also on target for the visitors.
Espanyol, who had Pablo Zabaleta sent off after 65 minutes, have lost five out of six games but remain fifth, three points clear of Sevilla.
Thierry Henry gave Barcelona the lead in the 35th, chesting down Deco's long pass before sliding a right-footed shot past goalkeeper Cesar Sanchez.
Zaragoza's Ricardo Oliveira ran onto Sergio Garcia's precise pass along the right before firing under Victor Valdes from a tight angle in the 53rd.
Zaragoza missed a chance in the 43rd when Diego Milito sent his penalty kick over the bar.
Real Madrid got off to the perfect start at the Ruiz de Lopera when Drenthe angled a shot in at the far post after fellow Dutchman Arjen Robben cut the ball across the area.
GOOD CHANCES
The visitors had two good chances to extend their advantage as Raul fired straight at Portugal keeper Ricardo and Robben lashed over with his weaker right foot.
Just as Madrid looked to be at their most comfortable, Betis hit back with two goals in four minutes.
Edu got in between Madrid defenders Marcelo and Sergio Ramos to power in a header at the far post from a cross by Mariano Pavone.
The second was an almost exact replica, except this time it was former Liverpool winger Gonzalez who outjumped Ramos and Marcelo to head in after Edu had turned fullback Michel Salgado inside out before crossing.
Madrid coach Bernd Schuster planned to rest Ruud van Nistelrooy before Tuesday's Champions League match against AS Roma but threw on the striker with half an hour to go.
The Dutchman almost equalised when he hit the post before Betis went on to claim their first points in three games to move four points clear of the drop zone.
