A first-half goal from Yannick Carrasco secured all three points for Atletico Madrid against Barcelona at home.
In doing so, they equaled Real Sociedad's tally of 20 points in the La Liga this season, while Diego Simeone beat Barcelona for the first time in La Liga history.
The highly-anticipated fixture began in frenetic fashion at the Wanda Metropolitano, as both sides looked sharp on the break.
Atleti took a while to get into their stride, but once they did, they produced more clear-cut opportunities than Barcelona. Marcos Llorente's thunderous effort struck the frame of the goal, while Messi and Antoine Griezmann also had attempts from inside the box.
Ousmane Dembele and Yannick Carrasco looked lively down their flanks, while Messi had a shot smothered away by Oblak.
Ter Stegen howler costs Barcelona on the night
Carrasco, who looked likely in the opening exchanges, outsmarted an onrushing March-Andre ter Stegen to hand Atletico Madrid a welcome lead. The Barcelona goalkeeper attempted to come off his line and made an absolute mess of the situation.
Barcelona's struggles off the pitch reflected on their performance in the second half. Even Messi failed to inspire his side, as he lacked sharpness and looked like a shadow of his former self.
To make matters worse, Gerard Pique was forced off due to a horrendous knee injury. Unfortunately for the Catalan giants, there is a serious shortage of central defenders amongst their ranks currently.
Atleti held on after taking the lead and outplayed their opponents on the night. After a point in the second half, it never looked like the visitors would threaten Atletico Madrid's advantage.