Ronaldinho is the second-top scorer in La Liga this season

Ronaldinho netted a stunning second-half free-kick and later headed his 15th goal of the season.

Further good news for Barca came when Argentine teenager Lionel Messi made his first appearance after three months out with a broken bone in his foot.

Barcelona are three points clear of Sevilla with Real Madrid in third.

Sevilla were held to a 0-0 draw by local rivals Real Betis and are now just two points ahead of Real Madrid.

Real won 2-1 on Saturday, a win in which David Beckham scored on his return to the starting line-up.

Beckham celebrates his goal against Real Sociedad

The 31-year-old equalised with a 25-yard free-kick in the 37th-minute of his first start since 20 December.

Madrid coach Fabio Capello had vowed Beckham would not play for Real again after he last month agreed to a lucrative move to Los Angeles Galaxy but had a change of heart last week.

"I am happy that Beckham scored," said Capello. "All the team is happy for him.

"He played a great game and deserves the credit. As I said before, the mark of an intelligent person is one who knows how to rectify his mistakes."

Fourth-placed Valencia lost ground on the leaders when they were beaten 3-0 by Getafe.