Barcelona moved two points clear at the top of the table on Saturday after notching a 1-0 win at home to Real Sociedad while title challengers Sevilla beat Real Madrid 2-1 in a highly charged encounter at the Sanchez Pizjuan.
Ronaldinho continued his superb run of recent form with his 11th league goal of the season when he steered a clever first-time shot into the far corner 16 minutes after the break to end Sociedad's stubborn resistance.
Sevilla's 100 percent home record looked to be in danger when they fell behind to a wonderfully struck free kick from David Beckham.
But in-form Sevilla striker Frederic Kanoute equalised soon after with a sharp finish to join Ronaldinho at the top of the scoring charts on 11 goals.
The UEFA Cup holders then claimed a deserved victory when substitute Ernesto Chevanton hooked a spectacular overhead kick into the bottom corner after a free kick 13 minutes from time.
Barca, who travel to Japan to take part in the Club World Cup on Sunday, lead the table on 33 points from 14 games, Sevilla move up to second on 31, while Real are a further two back on 29.
"We are delighted with the win and an important three points," goalkeeper Victor Valdes told Barca TV. "We are leaders and have now got a great tournament ahead of us."
Sociedad, who had not won at the Nou Camp in 15 years, frustrated Barcelona until the break but Ronaldinho broke the deadlock when he side-footed an angled shot past keeper Claudio Bravo after Ludovic Giuly picked him out with a pass from the right wing.
NERVOUS FINALE
Barca had to endure a nervous finale, however, when left back Silvinho was dismissed after two quick-fire bookings five minutes before the final whistle.
Valdes produced a stunning one-handed reflex save to tip Gaizka Garitano's header over the bar at the death and preserve the home side's lead.
Sociedad, the only Primera Liga side yet to win a match, remain in deep trouble with six points from 14 games, one above basement side Gimnastic Tarragona who host Levante on Sunday.
Former England captain Beckham put Real ahead against Sevilla when he curled the ball high across the area, over the head of keeper Andres Palop and inside the far top corner from a free kick wide on the left.
But Sevilla were back on level terms four minutes later thanks to a fine opportunist finish from Kanoute.
Luis Fabiano slammed a shot against the bar after turning inside Sergio Ramos on the edge of the area and the Mali striker was on hand to snap home on the half volley before the Real defence had time to react.
Ronaldo had a great chance to give Real the lead when he was put in the clear by Ruud van Nistelrooy only to have his final shot smothered by Palop as he burst into the area.
But it was Real who slipped to their third defeat of the season with Uruguayan Chevanton's spectacular winner after Julien Escude had nodded on Daniel Alves's free kick.