Karim Benzema's exquisite assist set up Casemiro for Real Madrid's winner as they edged out Espanyol 1-0 to move two points clear at the top of La Liga.
Benzema unpicked the Espanyol defence on the stroke of half-time with a sublime back-heel that bewildered two defenders and laid the opener on a plate for Casemiro.
It was a cruel blow on rock-bottom Espanyol at the end of an encouraging first-half display which saw forward Wu Lei spurn a host of chances to give their faint hopes of avoiding relegation a timely shot in the arm.
Chances were at a premium in the second period but Real maintained a measure of control, securing their fifth-consecutive victory since the restart as they capitalised on Barcelona's draw at Celta Vigo to return to the summit of La Liga with six games to play.
Espanyol remain rooted to the foot of the table, 10 points from safety with their 26-year stay in La Liga in jeopardy.
Espanyol: D Lopez (6), V Gomez (6), Espinosa (6), Cabrera (6), Didac (5), Embarba (6), Roca (6), David Lopez (6), Darder (6), De Tomas (6), Wu (5).
Subs: Pedrosa (6), Calleri (5), Melendo (5), Lozano (5).
Real Madrid: Courtois (8), Carvajal (7), Ramos (8), Varane (8), Marcelo (7), Casemiro (8), Kroos (6), Valverde (6), Isco (6), Hazard (6), Benzema (8).
Subs: Vinicius (5), Rodrygo (5).
Man of the Match: Karim Benzema
How Real remained in charge of title race
Barcelona's dramatic draw at Celta Vigo on Saturday opened the door for Real Madrid to seize control of the La Liga title race but the magnitude of what was at stake looked to weigh on their shoulders.
Sergi Darder almost fired Espanyol ahead inside three minutes after Wu Lei raced in behind the static Madrid defence, but Raphael Varane produced a crucial block.
That kicked Real into gear as Casemiro and Sergio Ramos had brief glimpses of the Espanyol goal before Casemiro headed their best opening over on 14 minutes when Varane's near-post flick directed a corner onto the unmarked Brazilian six yards out.
- Espanyol made six changes from their defeat at Real Betis.
- Marcelo, Casemiro, Isco and Toni Kroos return as Real made four changes from the win against Mallorca.
Espanyol remained a threat though, with Marc Roca's in-swinging free-kick forcing a fine save from Thibaut Courtois on 20 minutes before the dangerous Wu turned up another glorious opening when he blazes over the angle of post and bar after racing through on goal.
Ramos and Benzema forced saved from former Real Madrid stopper Diego Lopez as half-time approached, but just as Espanyol thought they had reached the interval unscathed, the visitors' quality came to the fore.
Boxed in by two Espanyol defenders, Benzema's brilliant back-heel sent the ball into the path of the late-arriving Casemiro, and the Brazilian fired Real into the break ahead.
Within seconds of emerging from the break another chance fell for Wu, but again the China international's finish was found wanting as he fired straight at a thankful Courtois.
With Real content at preserving their lead and Espanyol keen to avoid further damage, the game drifted towards its conclusion, and by the time the hosts mounted a late rally they were unable to regain momentum as Real returned to the top of the table and left Espanyol floundering at the foot.
Real Madrid host Getafe on Thursday at 9pm, while Espanyol travel to Real Sociedad at the earlier time of 6.30pm.
La Liga round-up: Eibar edge closer to survival, Villarreal boost CL hopes
Eibar edged closer to La Liga survival with a 2-1 victory at Granada.
Kike Garcia struck the winning goal in the 69th minute to restore Eibar's lead after Granada forward Roberto Soldado had cancelled out Pablo de Blasis' opening goal, giving the Basques only their second victory on the road this season.
Eibar started the day in the final spot outside the relegation zone, but victory takes them up to 15th on 35 points, nine clear of the relegation places with six matches left to play.
The result means that third-bottom Real Mallorca are eight points from the safety, while 19th-placed Leganes are nine adrift and bottom side Espanyol 10 behind.
Levante effectively sealed their top-flight status with a thumping 4-2 win at home to Real Betis.
Victory sees Levante move up to 12th on 41 points, while Betis stay 13th, 11 points above the bottom three.
Elsewhere, Villarreal beat neighbours Valencia 2-0 to boost their chances of a top-four finish, while further denting their rivals hopes of returning to the Champions League.
Former Valencia forward Paco Alcacer opened the scoring with a superb volley on the turn in the 14th minute but opted against celebrating against the club where he began his career.
Alcacer's strike partner Gerard Moreno scored an even better goal to secure all three points.
The result sees them up to fifth on 51 points, three back from fourth-placed Sevilla with six games remaining in the season. By contrast, Valencia, who are eighth, have picked up just four points since the campaign resumed and are without an away win in the league since December.