Barcelona 4 - 1 Numancia
A brace from the irresistible Lionel Messi and one apiece from Samuel Eto'o and Thierry Henry saw off a plucky Numancia side who had a goal controversially disallowed and pulled a goal back to make it 2-1 on the hour mark.
The visitors had captain Cesar Palacios dismissed late on for a second yellow card.
Barcelona dominated the match but, despite chances for Daniel Alves, Gerard Pique, Xavi, Messi and Andres Iniesta, it was goalless at half-time and could even have been 1-0 to Numancia had Javier Del Pino's 18th-minute header not been harshly ruled out for an alleged push on Iniesta.
Alves hit the top of the bar with an audacious lob, Pique drilled wide from the edge of the box, Xavi and Messi had consecutive shots bravely blocked by Sergio Ortega and Boris, Juan Pablo denied Iniesta with a wonderful stoop and Juanra denied Messi again with a superb last-ditch tackle.
But somehow it was goalless at the break, although parity did not last very long as Messi had the simplest of finishes three minutes after the restart thanks to great work from the marauding Alves.
It was 2-0 three minutes later when Iniesta's pass ricocheted into the path of Eto'o, who held off Ortega and finished past Juan Pablo.
Jose Barkero's wonderful free-kick gave the visitors hope, but Henry sent a low deflected shot off the foot of Palacios 10 minutes later and Messi sealed the rout with a tap-in after his initial shot was blocked by Juan Pablo, who did not deserve to be beaten four times.
By the end it could have been six or seven, with Messi forcing another good save from Juan Pablo and hitting the crossbar, while Eto'o missed two clear-cut chances to draw level with Messi on 22 goals scored in all competitions.
Real Madrid can close the gap to 12 points if they beat Deportivo but Barcelona - with 53 points from a possible 60 and an average of over three goals a game - will almost certainly win the title.