Cameroon international Samuel Eto'o extended his La Liga lead with his 20th and 21st goals of the season. Right back Daniel Alves scored the third goal.
"Alves never tires and is an extraordinary player and Eto'o helps us a great deal with his goals and his sacrifice," said Barca coach Pep Guardiola.
Third-place Sevilla and fourth-place Valencia fell further off the pace when they both lost -- Sevilla, 2-1, at home to city rival Betis and Valencia at Osasuna, 1-0.
Italian-American striker Giuseppe Rossi scored twice to give Villarreal a 2-1 win over Numancia that moved the Yellow Submarine into a tie with Valencia.
Abel Resino got off to a winning start as Atletico Madrid beat Recreativo Huelva, 3-0, thanks to two goals by Diego Furlan and one by Sergio Aguero.