A superbly taken goal by Ronaldo saw Real Madrid come from behind to draw with Barcelona, despite being reduced to 10 men after Roberto Carlos was sent off in the 24th minute.
Barça lead their great rivals by 11 points at the top of La Liga with seven games to play, but their performance lacked the cohesion of the vintage Bernabeu display which saw Frank Rijkaard's side beat Real 3-0 in November.
Since that game, Barça fans have regularly gloated about their current pre-eminence, the intensity of their dislike of all things Madrid evident when the visitors' team bus was pelted with cans and bottles approaching the stadium. The response of some Real players - that of raising a solitary finger - hardly quelled the febrile atmosphere.
Barcelona enjoyed the better of the opening exchanges, Mark van Bommel shooting wide after three minutes following a through ball from Ronaldinho.
The Brazilian was responsible for giving Barça the lead when Van Bommel went down easily following a tackle by Carlos in the 21st minute. Ronaldinho converted the controversial penalty while Carlos was booked for protesting against the decision. He was sent off just three minutes later, the red mist again evident as he complained following a challenge on Henrik Larsson.
"The sending-off was an overly harsh decision and that made it a particularly difficult for us," said Ronaldo, who was frequently taunted with chants of "Fatty, fatty". "Roberto told me he had done nothing to offend the referee. The referees seem to be against us, blowing for non-existent penalties and free-kicks. With 10 players, we had to struggle for our lives."
It may have been a battle but Real covered space and closed down Barça's attacks efficiently. Zinedine Zidane is a Rolls-Royce of a player running on his last drops of petrol, but he helped stem the surging Barça attacks, while goalkeeper Iker Casillas produced several fine saves from Samuel Eto'o and Larsson.
The only injustice about Real's equaliser was that it came against the run of play. Ronaldo ran onto a clever through ball from Julio Baptista nine minutes before half time, holding off the defence before lifting the ball beautifully over goalkeeper Victor Valdes.
The goal and the loss of versatile defender Thiago Motta with a groin strain just before half-time, broke the home side's momentum. Motta is doubtful for Wednesday's Champions League quarter-final second leg with Benfica, one of several injuries that will concern Rijkaard.
As expected, Barça attacked in the second half, Eto'o hitting the outside of the post a minute after the interval, while Larsson, playing in his last clasico before his return to Sweden, missed two late chances. "It was just one of those nights when things didn't go for me," Larsson said. "It was disappointing because we had enough chances to win the game."
Barcelona (4-3-3): Valdes; Van Bronckhorst, Oleguer, Puyol (Gabri, 89), Motta (Belletti, 39); Iniesta, Deco, Van Bommel (Giuly, 56); Ronaldinho, Eto'o, Larsson. Substitutes not used: Jorquera (gk), M Lopez, Rodri, Ezquerro.
Real Madrid (4-2-3-1): Casillas; Cicinho, Ramos, Bravo, Carlos; Baptista, Guti (Garcia, 89); Beckham, Zidane (Gravesen, 78), Robinho (Mejia, 34); Ronaldo. Substitutes not used: D Lopez (gk), Salgado, Raul, Cassano.
Referee: L Medina Cantalejo.Reuse content