Casemiro scored the only goal as injury-hit Real Madrid earned a 1-0 win at Real Valladolid to close the gap on LaLiga leaders Atletico Madrid to three points.
Atletico lost for just the second time this season in the league earlier on Sunday morning (AEDT) to open the door, and their city rivals took full advantage at Estadio Jose Zorrilla with a fourth win in a row, the last three of those secured without conceding.
Zinedine Zidane's side failed to register a single shot on target in the first half of a league game for the second time this season and required Thibaut Courtois to produce three big saves to keep them level.
But Madrid, who were without striker Karim Benzema and eight other first-team players, made the breakthrough thanks to Casemiro's 65th-minute header and saw the game out to up the pressure on Atleti, who have a game in hand to play.
Courtois made the first of his key saves inside seven minutes to keep out Fabian Orellana's poked effort and then Saidy Janko's follow-up shot as Valladolid, also denied a strong penalty shout for Casemiro's tackle on Kike Perez, made a bright start.
Casemiro powered a free header over the crossbar from the edge of the six-yard box from Madrid's only clear-cut legitimate opportunity of a lacklustre first half, though Mariano did correctly have two goals ruled out for offside.
Lucas Vazquez fired in Madrid's first on-target attempt six minutes into the second period - a simple stop for Jordi Masip to make in the Valladolid goal - after Casemiro had guided another header off target.
The visitors would have fallen behind three minutes later if not for Courtois, who saved Orellana's volley and spared the blushes of team-mate Ferland Mendy in the process - the full-back having crossed the ball straight to the opposition player.
However, it proved a case of third time lucky for Casemiro as he headed Toni Kroos' superb set-piece back across goal and away from Masip to open the scoring for the reigning champions.
Valladolid had another penalty appeal rejected, this time for Nacho Fernandez's challenge on Shon Weissman, as Madrid held on for what could yet prove to be a crucial win in the title race.
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Atletico's defeat to Levante - their first loss at home in the league since December 2019 - was the third time in four matches they have dropped points.
In contrast, Zidane's Los Blancos have taken 12 points from 12 over the same period and the gap at the top now stands at just three points, though Atleti do have a game in hand.
All Real Madrid can do is keep winning and hope their neighbours continue slipping up ahead of their huge showdown at Wanda Metropolitano, which is scheduled for March 7.
Another clean sheet for Courtois
Madrid have now kept out the opposition in their last three league games and a large part of that is down to the impressive form of Courtois in goal.
The Belgium keeper made five saves in total against Valladolid, three of those right out of the top drawer. Without him, Madrid could well have been on the end of a shock loss.
Benzema massively missed
Madrid managed just two attempts on target all game in the absence of star striker Benzema, who missed out with a knock and is doubtful to face Atalanta in the Champions League in midweek.
Mariano was tasked with filling the void here and the 27-year-old did not really make the most of his opportunity. He had two goals rightly ruled out for offside and touched the ball just 18 times during his 66 minutes on the field, compared to 24 for Courtois during the same period.
After taking on Atalanta in the Champions League on Wednesday, Madrid switch focus back to LaLiga on March 1 with a home game against Real Sociedad. Next up for Valladolid is a trip to Celta Vigo in eight days' time.