On Saturday after beating Barcelona, Atletico Madrid has moved nine points clear of Barcelona.
Yannick Carrasco finished brilliantly from range after mistakes from Gerard Pique and Marc-Andre ter Stegen left the goal gaping but Barca, and a below-par Lionel Messi, failed to respond at the Wanda Metropolitano.
Instead, Atletico recorded their first league victory over Barcelona in 10 years, which puts them three points ahead of Real Madrid, with a game in hand, and leaves their opponents languishing in 10th.
Diego Simeone’s men sit second in the table, level on points with early leaders Real Sociedad.
Real Madrid had earlier been held to a 1-1 draw by in-form Villarreal, another slip-up for the reigning champions to enforce the sense that this could be Atletico’s year.
And beating Barcelona in La Liga for the first time since 2010 — before Simeone arrived as coach — will do wonders for the team’s belief and extends what is now a considerable advantage in the table.
It also extends Atletico’s unbeaten run in the league to 24 matches.
Another disappointing day for Barca was soured further by the sight of Pique hobbling off in tears with what looked a knee injury.
Pique was hurt during a collision with Angel Correa and was in distress as he departed.
Antoine Griezmann almost put Barca in front against his old club while Marcos Llorente went closest for Atletico, skimming the crossbar after a neat exchange between Kieran Trippier and Correa down the right.
Messi might have scored but was uncharacteristically hesitant, with an even half about to finish goalless until two errors gifted Atletico the lead.
Pique was caught out of position after a heavy touch and Mario Hermoso did well to free Carrasco.
Ter Stegen, already upfield, rushed out to fill the gap Pique had left but Carrasco’s first touch feathered the ball through the goalkeeper’s legs before a curling finish from 50 yards sent the ball into the open net.
Clement Lenglet should have equalised but headed Messi’s cross straight at Jan Oblak yet Barcelona were far from dominant and Messi struggled for his usual influence.
Philippe Coutinho came on and Pique hobbled off. Messi floated a free-kick wide and saw a shot blocked before substitute Martin Braithwaite was given a late chance after a poor kick by Oblak.
But Barca were unable to find a way through.