Madrid made sure not to pass up the opportunity to build a gap at the summit as Casemiro scored following a wonderful Karim Benzema assist in an entertaining if ultimately narrow away victory.
The capital club have control of the title race with just six matches remaining, although it was not all one-way traffic at RCDE Stadium despite bottom side Espanyol's accommodating defending.
Madrid looked similarly shaky at times in the first half as Sergi Darder saw an early deflected shot trickle wide before Wu Lei wastefully blasted over.
Former Madrid goalkeeper Diego Lopez scrambled to keep out an ambitious Casemiro attempt and watched both Sergio Ramos and the Brazil international head over, the captain missing the target from point-blank range.
Benzema was next to try his luck and draw a save from Lopez, whose busy outing continued with a double stop from Casemiro and Eden Hazard in a goalmouth scramble prompted by his own failure to deal with a high cross.
3 - @realmadriden striker Karim Benzema is the third @LaLigaEN player to reach double figures for both goals (22) and assists (10) in 2019/20 in all competitions, after Lionel Messi (26 & 21) and Luis Suárez (16 & 11). Genie. pic.twitter.com/aFKjOASBOI— OptaJose (@OptaJose) June 28, 2020
Casemiro's fifth effort before half-time finally evaded Lopez to break the deadlock, though, as Benzema teed up his team-mate with a cute backheel through Bernardo Espinosa's legs.
Madrid's momentum was slowed by the break, yet subsequent speculative Espanyol efforts from distance did not cause Thibaut Courtois significant concern as another win was sealed.
What does it mean? Madrid reinvigorated since restart
Defeat to Real Betis in March saw Madrid hand pole position back to Barcelona, but the coronavirus pandemic swiftly prompted the suspension of the season.
Zidane's side have entertained since the restart and could have run up a handsome scoreline against Espanyol. Crucially, though, they have won five straight matches, striking a balance between style and substance, while Barca have twice dropped points.
Casemiro in control
Nominally a holding midfielder, Casemiro provided Madrid's chief attacking threat in the first half. He appeared to be involved in each and every attack and deserved a goal long before it arrived courtesy of a gorgeous piece of skill from Benzema that meant, this time, Casemiro could not miss.
Wu wide of the mark
Madrid may have given up more chances than usual in recent weeks, but opponents must still make sure to take their opportunities when they arrive. Wu's profligacy saw Espanyol fail to do so. He should have hit the target when well placed in the first half and then aimed a tame shot into Courtois' clutches shortly after the break.
Madrid host stuttering Getafe on Thursday, the same day Espanyol's unlikely bid to avoid the drop takes them to Real Sociedad.