Valencia closed the gap on league leaders Barcelona to six points after beating the reigning Spanish champions 1-0.
The hosts inflicted Barca's second league defeat in seven days with Spanish international striker David Villa getting the only goal of the game but many pundits will say that the Catalan club's defeat was more self-inflicted.
Villa intercepted a poor kick from Barca goalkeeper Victor Valdes, who was just outside his area and trying to pass to Carles Puyol, and deftly chipped it into the net just before half time.
"I feel sorry for Victor, we are good friends when we are together in the national side, but that's the way it goes," said Villa, who got his 15th goal of the season on Sunday.
"We won this game in the first half and then just hung on in the second," admited Villa, who chose Valencia rather than the European champions Liverpool when he moved from Real Zaragoza last summer.
Barcelona had their chances in the second half.
Valencia keeper Santiago Canizares instinctively stopped a point-blank Henrik Larsson shot with his legs and an Edmilson header skimmed just past the post but, despite a frantic final 15 minutes, Barca couldn't salvage a point.
"I think we were the slightly better side but we just couldn't find the net," lamented Edmilson.
Barcelona have 52 points from 23 games but Valencia are now only six points behind after going 12 games unbeaten.
Real Madrid started the weekend in third and ended it in the same position, one point behind Valencia, after a 2-0 win at struggling Athletic Bilbao on Saturday.
Goals from Robinho and Raul Bravo maintained the Spainish giant's unbeaten league record since the start of the year and sent the Basque side down to the penultimate place in the Spanish first division.
"This was a Real Madrid with great personality," said coach Juan Ramon Lopez Caro, reflecting on the fact that his team had bounced back from the 6-1 midweek mauling at Real Zaragoza in the Spanish Cup.
One negative note for Lopez Caro was that his Uruguayan midfielder Pablo Garcia suffered a snapped ligament in his left knee and is expected to be out for at least six weeks.
Celta Vigo remain fifth after a 1-0 win over Villarreal on Sunday.
Fernando Baiano got the only goal of the game after 37 minutes, the Br azilian scoring from the penalty spot after Villarreal defender Gonzalo Rodriguez had pushed over David Silva in the box.
At the other end of the table, Real Mallorca stay at the foot of the table despite a 1-1 draw with Getafe.
Juan Arango put the home side ahead after 67 minutes, hammering home a Leonardo Pisculichi pass from almost exactly the penalty spot.
However, Mallorca have been guilty of shoddy defending all season and it came back to haunt them again when Vivar Dorado equalised from close range 11 minutes from the end.
Mallorca have now gone nine games without a win and the future of coach Hector Cuper is starting to look bleak.
Alaves have been mired in relegation trouble all season but their 3-2 victory over fellow strugglers Malaga saw them move out of the drop zone.
It was the Basque side's third victory in five games since Juan Carlos Oliva took over at the helm last month.
An own goal from Malaga's Cesar Navas, who turned a shot from Nene into his own net, put Alaves ahead just before the break.
"I never thought we got as much luck as we deserved in this match. In the first half we had seven or eight opportunities to score," commented Oliva about his rapidly improving side.
Australian striker John Aloisi then stabbed the ball home four minutes after half time for his fifth goal in as many games before Rodolfo Bodipo added Alaves' third of the afternoon seven minutes later.
Late goals from Duda and Antonio Hidalgo narrowed the gap between the two sides but Malaga's response was too little, too late.