Goals from Puyol, Messi (2), Pedro and Villa gave Barcelona an easy win against Real Sociedad, a great start for new coach Tito Vilanova. Castro was the scorer for Real Sociedad.
Real Madrid began their La Liga campaign with a 1-1 draw against Valencia, Higuain putting Real ahead before Jonas grabbed an equaliser just before the break.
Athletic Bilbao and Betis were involved in an eight goal thriller, Betis eventually coming out on top 3-5. Castro, Molina and Beñat put Betis three up before half time but De Marcos and San José with two goals saw the teams back on level terms.
Pozuelo and Molina, with his second of the night, then ensured victory for the visitors late in the second half.
There are still three matches to be played on Monday night.