Atletico Madrid's top-four chances suffered another blow as they slumped to a surprise 1-0 defeat at home to Levante, who became the first away team to win two LaLiga games at the Wanda Metropolitano.
Diego Simeone's men were overtaken in fourth by Barcelona 10 days earlier and the champions will trail them by three points if the Blaugrana go on to win their game in hand.
Atletico remained level at half-time despite an underwhelming display, but they were punished in the 54th minute by Gonzalo Melero's crisp finish.
A penalty award in favour of Atletico was then reversed soon after and, although Simeone threw attacking players on towards the end, they could not salvage a point.
Atletico offered precious little in a first half that Levante dominated for spells with 60 per cent possession.
The hosts were indebted to Jan Oblak as Levante looked destined to take the lead in the 22nd minute, the goalkeeper making a vital one-on-one save to deny Jorge de Frutos after Stefan Savic's miscued header.
Levante deservedly went ahead early in the second half, De Frutos teeing up Melero for a first-time finish that beat Oblak at his near post.
Atletico thought they had the chance to level from the spot when Geoffrey Kondogbia's shot was blocked by an arm, but referee Jose Luis Munuera Montero overturned his decision due to Marcos Llorente straying offside in the build-up.
A chaotic end saw Angel Correa have an equaliser disallowed for an apparent foul on Martin Caceres by Jose Gimenez, before Mickael Malsa struck the crossbar for Levante from 40 yards – not that it mattered as the visitors clung on for a massive win.
What does it mean? Atletico's woes reach the stands
Atletico fans have had just cause for frustration in recent weeks given how leaky they have been at the back, but this was the first time a divide could be seen between the support and certain players.
Jose Gimenez made a couple of gestures towards the home fans in the second half, seemingly urging them to stop jeering the team.
He was subsequently whistled every time he got the ball, and it highlighted what is quickly becoming a toxic situation at Atletico.
Pepelu shows his class
In an otherwise difficult season for Levante, midfielder Pepelu has been a bright spark. He was lively again here, his two key passes the joint-most of anyone on the pitch, but he also worked hard off the ball, making a team-high three interceptions.
Atletico's creators lacking craft
Rodrigo de Paul's first season at Atletico has largely been a disappointment. He was again here, failing to lay on a single key pass – though he was not the only one.
Matheus Cunha's recent form has earned him a few more starts, but he was also withdrawn just after the hour having not registered a shot or key pass.
What's next?
Atletico face Osasuna in Pamplona on Saturday before turning their attentions to the Champions League and the visit of Manchester United next Wednesday.