Argentine midfielder Santiago Solari scored in the 54th minute for Madrid, which had Luis Figo ejected 15 minutes later. Substitute Patrick Kluivert leveled in the 58th minute.

Meanwhile, midfielder Jorge Lopez netted a 13th-minute penalty to give Valencia a one-point lead at the top of the standings with four rounds remaining.

Valencia has 71 points from 34 games, while defending champion Madrid has 70. Barcelona is next with 66 points, four more than Deportivo de La Coruna.

Madrid's defeat, its second in succession at home, leaves it in danger of ending the season without a trophy.

"We're going to battle on. The race is not over yet," Madrid captain Raul Gonzalez said. "Although we realize we have to start winning now otherwise we'll hand the title to Valencia."

Barcelona's victory, its first in the Spanish league at Madrid's citadel for six seasons, extended its unbeaten run to 16 matches.

"The ejection of Figo was key," Barcelona coach Frank Rijkaard said. "(Goalkeeper) Victor Valdes worked miracles but we won with a great team."

Madrid, which lacked injured ace Ronaldo, made a slow start but laid siege to its goal in the closing stages of the first half.

Valdes shone to thwart Raul in the 37th minute, with defender Carles Puyol then heading off the goalline as Roberto Carlos sent the rebound toward goal.

Two minutes later, Raul sent the ball onto the bar after Valdes had parried an inswinging David Beckham free kick, with Figo's follow-up header parried on the line by the Barcelona 'keeper.

Valdes performed more wonders early in the second half when he denied Zinedine Zidane and Figo in quick succession only for Madrid to take the lead moments later. Beckham's cross was knocked away from goal by Roberto Carlos and Solari drove the ball past the diving Valdes.

Rijkaard quickly reacted by bringing on Kluivert and veteran midfielder Luis Enrique Martinez, and within a minute the Dutch striker had headed home an equalizer after left back Giovanni van Bronckhorst had beaten the offside trap and lobbed over Madrid goalkeeper Iker Casillas.

Figo, whose move from Barcelona to Madrid in 2000 infuriated the Catalan team's supporters, then received his second yellow card of the game for a wild tackle on Puyol and allowed Barcelona to take charge of the game.

Ronaldinho, who had been quiet up to then, burst into life in the 77th minute and beat three Madrid players before crossing for Kluivert to head just over the bar.

Nine minutes later, the Brazilian star created the winning goal when he cheekily lifted the ball over Madrid's defense and Xavi, played onside by Raul Bravo, flicked the ball past Casillas.

News reports said 800 police officers were at the game, with spectators who carried bags into the stadium searched as a consequence of the train bombings in Madrid last month, which killed 191 people.

Valencia, unbeaten in seven league games, failed to take full advantage of Madrid's setback in a hard-fought game in Bilbao.

Valencia got off to a flying start when Lopez converted a penalty awarded after Jesus Maria La Cruz had handled.

The Basque team battled back and left back Asier del Horno netted in the 31st minute with a powerful header from a free kick by midfielder Fran Yeste.

Valencia played a containing game for the rest of the match and its few counterattacks barely threatened the Bilbao defense.

Other results Sunday were: Celta de Vigo 1, Osasuna 0; Real Betis 2, Real Sociedad 1; Valladolid 1, Mallorca 3; Zaragoza 4, Sevilla 4; Racing de Santander 0, Albacete 2; and Villarreal 1, Murcia 0.

Osasuna midfielder Inaki Munoz netted involuntarily as he tried to tackle Brazilian midfielder Everton Giovanella in the 50th minute to gift Celta only its third home win of the season.

Celta, which despite its relegation worries reached the second round of this season's Champions League, has gone four games undefeated under caretaker coach Ramon Carnero although it stays 19th with 36 points. Osasuna stays sixth with 46.

Real Betis ended Real Sociedad's three-match run without a defeat, thanks to first-half goals by midfielder Benjamin Zarandona, who was later ejected, and striker Dani Martin.

Turkish striker Nihat Kahveci replied for Sociedad, which missed two penalties. Valery Karpin and substitute Darko Kovacevic were the culprits.

Mallorca moved out of the bottom three places with an away win against fellow struggler Valladolid.

Uruguayan forward Fernando Correa scored twice and Serbian and Montenegrin striker Andrija Delibasic got another, with midfielder Chema Jimenez replying for Valladolid.

Zaragoza striker David Villa grabbed four goals, although his team could only draw 4-4 with Sevilla.

Villa took his season's tally to 17 with three shots and a penalty, while midfielder Javi Casquero netted two of Sevilla's goals. Brazilian midfielder Julio Baptista also scored with a spot kick, which led to the dismissal of Paraguayan defender Delio Toledo, and substitute Carlos Dominguez netted an injury-time equalizer.

Struggling Albacete gained a 2-0 win on its visit to fellow struggler Racing de Santander. Uruguayan international striker Antonio Pacheco and midfielder Pablo Redondo scored on either side of halftime.

Villarreal captain Quique Alvarez netted a 68th-minute goal as his team, which seemed tired by the goalless first leg of its UEFA Cup semifinal match with Valencia on Thursday, edged already-relegated Murcia 1-0.

On Saturday, Deportivo drew 1-1 with Malaga, while Espanyol downed Atletico de Madrid 3-1.