Real Madrid's Pepe (R) celebrates with teammates after scoring against Barcelona during their Spanish first division "Clasico" soccer match at the Santiago Bernabeu stadium in Madrid October 25, 2014. [Photo/Agencies]

Suarez then almost set up Messi for a second goal with a pinpoint cross to meet the Argentine's run behind the defense, only for Casillas to make an excellent save with his leg to push the ball wide in the 21st.

But just when Barcelona was playing its best, Marcelo made an incursion down the left side and sent in a low cross that Gerard Pique stopped with his arm as he fell.

Ronaldo stepped up to take the resulting penalty and fired it into the corner to leave goalkeeper Claudio Bravo's league record of not conceding a goal at eight games and 35 minutes.

Barcelona's defensive mistakes mounted in the second half as Madrid took full control.

Madrid went in front when Barcelona conceded a corner following Javier Mascherano's poor pass, giving Pepe a chance to thump in Toni Kroos' corner after he shed his marker.

A madcap series of errors by Barcelona let Madrid put the result beyond doubt.

Ivan Rakitic, in his first action since replacing Xavi, flubbed his corner kick and Iniesta and Mascherano stared at one another while Francisco "Isco" Alarcon won the clearance near midfield. Benzema ended up with the ball to finally slot it home, with the ball hitting the post but going in this time.

"Madrid deserved to win," said Barcelona manager Luis Enrique. "This is a loss that clearly leaves Madrid as good or better than we are and we have to correct the mistakes we made today."

Valencia moved into third, two points behind Barcelona, with a 3-1 win over Elche.

Elsewhere, Athletic Bilbao won 1-0 at Almeria, Eibar drew 1-1 at home with Granada, and Real Sociedad drew 1-1 at Cordoba.