An unstoppable drive from Zinedine Zidane, two trademark opportunist strikes from skipper Raul and a debut goal from midfielder Thomas Gravesen sealed an emphatic victory. Barcelona host Atletico Madrid on Sunday.
The race for the title has been effectively reduced to a two-horse affair after champions Valencia could manage only a 3-3 draw at struggling Real Sociedad, a result that left them nine points adrift of Real in third place.
Espanyol are three points further back in fourth and are likely to drop down the table after Sunday's matches.
Turkish forward Nihat Kahveci capped a brilliant performance with a classy last-gasp strike to earn Sociedad their first point in six outings.
Valencia took the lead against the run of play when Italian striker Marco Di Vaio fired home in the 10th minute before Nihat made it 1-1 with a spectacular volley on the stroke of halftime.
The Basques looked to have secured a valuable first win of the year when midfielder Mikel Aranburu poked home from two metres out after Canizares had been unable to hold a vicious drive from Nihat 10 minutes from time.
A Ruben Baraja header and a superbly struck Xisco volley in the 89th minute gave the visitors an undeserved lead until the brilliant Nihat intervened again to earn his side a vital point.
SHARP SAVE
At the Bernabeu, Ronaldo looked certain to score in the 12th minute when he rounded Espanyol keeper Carlos Kameni. But the ball ran away from him and he fired into the side netting.
Real took the lead moments later, thanks to brilliant skill from Zidane.
The Frenchman, in poor form of late, plucked the ball out of the air with his toe on the edge of the area, left Argentine defender Hugo Ibarra sprawling on the grass with a double step-over and then blasted into the roof of the net.
It was not all Real and keeper Iker Casillas had to make two fine reflex saves to deny midfielder Ito midway through the half before Raul stretched his side's lead with a typical strike.
The Real Madrid skipper poked in on the rebound after Kameni had turned a venomous drive from the lively Figo on to the post on the half hour.
Real eased up after the break, although Raul made it 3-0 when he stole in front of the Espanyol defence to divert a Santiago Solari pass into the net in the 75th minute.
Former Everton midfielder Gravesen wrapped up a comprehensive victory five minutes from time when, after coming on as substitute, he guided a shot past Kameni from the edge of the area.
