Real's players embraced each other when the final whistle arrived to signal a fifth consecutive victory which took them top on 71 points after 32 games.
Real Madrid's Karim Benzema produced an audacious back-heeled assist for Casemiro to score as they beat Espanyol 1-0 away on Sunday to capitalise on Barcelona's slip-up a day earlier and move two points clear at the top of La Liga.
Brazilian midfielder Casemiro slid to the ground to guide the ball home on the stroke of halftime after being played in by a stroke of genius from Benzema, who dragged the ball through the legs of his marker Bernardo Espinosa to find his teammate.
Real's players embraced each other when the final whistle arrived to signal a fifth consecutive victory which took them top on 71 points after 32 games. Barca, who were held to a 2-2 draw at Celta Vigo on Saturday, are second on 69.
Casemiro was Real's most dangerous player and nearly opened the scoring early on with a wild shot from his own half which forced Espanyol goalkeeper Diego Lopez to scramble back towards his line and push the ball away.
Casemiro then somehow missed the target with a header when he appeared unmarked from close range, but he soon made amends thanks to the quick-thinking of Benzema.
"It was a nice assist but the goal was more important, Casemiro did well and got us three important points after a very difficult game," said Benzema.
Real looked in control for most of the match but had to endure two nervy moments in the final stages.
Espanyol's Espinosa was inches away from connecting with a ball which flashed across the face of goal while Real defender Marcelo was forced to block a shot in added time which almost deflected the ball into his own net but it skidded wide instead.
Espanyol, who were playing their first game under caretaker coach Francisco Rufete after he became their fourth manager of a troubling campaign, remain rooted to the bottom of the table on 24 points, 10 away from escaping the relegation zone.
The Barcelona-based outfit look destined to be relegated after spending the last 26 years in La Liga but they put up a strong fight at their empty stadium and Chinese forward Wu Lei twice came close to giving them the lead in the first half.