Atletico Madrid pulled off their first La Liga win over Barcelona in more than a decade as Yannick Carrasco capitalised on a blunder from Barca keeper Marc-Andre ter Stegen to secure a 1-0 victory at an empty Wanda Metropolitano on Saturday.
Belgian winger Carrasco broke the deadlock at the end of the first half, pulling off a classy backheel to knock the ball through the legs of Ter Stegen and keep his composure in front of goal after the German had charged out of his area.
Lionel Messi had won the fixture last season with a late solo goal but the Barca captain had a match to forget this time, creating very little danger and appearing hesitant in front of goal.
Barca's former Atletico forward Antoine Griezmann missed the target in each half while defender Clement Lenglet had their best chance when, unmarked, he could only send his header straight into the arms of keeper Jan Oblak.
The win moved Atletico up to second in the standings, level on 20 points with leaders Real Sociedad, while Barca are down in 10th place with 11 points after a third defeat in eight league games under Ronald Koeman.
"A team like Barca cannot afford to concede a goal like that," said the Dutchman.
"It was our fault, it's not good and we can't let something like that happen again."
The Catalans' pain was compounded by the sight of defender Gerard Pique limping off the pitch in tears after a challenge from Angel Correa.
A club medical report eased initial fears that Pique had torn knee ligaments and said he had strained them, meaning he will be out for about six weeks.
Barca's players had come out for the game wearing T-shirts in tribute to their teenage striking sensation Ansu Fati who recently underwent knee surgery and they were also missing midfield anchor Sergio Busquets, a veteran of the fixture.
Atletico were without joint-top scorer Luis Suarez, who was deprived of a reunion with his former side after testing positive for COVID-19, while midfielders Hector Herrera and Lucas Torreira were also unavailable but they well deserved their victory.
Marcos Llorente nearly gave Atletico an early lead when his shot crashed off the bar, while it took a brilliant save from Ter Stegen to keep out a vicious distance strike from Saul Niguez.
While Barca had their chances to level, Atletico comfortably saw out the victory and coach Diego Simeone punched the air when the whistle came to signal his first league victory over Barca since he took charge of Atletico in 2011.
"It was our turn to win today but it won't change our objectives," said the coach.
"We knew exactly how we needed to play and that we would have to work as hard in attack as in defence."
Elsewhere, a severely depleted Real Madrid conceded a fourth penalty in two games as they drew 1-1 at Villarreal, dropping points for the second game in a row.
Zinedine Zidane's side were missing seven players through injury and illness, including the indispensable trio of Sergio Ramos, Karim Benzema and Casemiro, but the champions went ahead in the second minute with a diving header from Mariano Diaz.
Villarreal forward Gerard Moreno levelled from the spot in the 76th minute after substitute Samuel Chukwueze had been felled by Madrid keeper Thibaut Courtois, who also let in three penalties in the 4-1 defeat at Valencia two weeks ago.
Unai Emery's Villarreal were much improved in the second half and had spurned numerous chances before Moreno's leveller. They went searching for a winner and almost found one through Japanese teenager Takefusa Kubo, who is on loan from Madrid, but Courtois stood firm to make the save.
Real are fourth in the standings on 17 points, while Villarreal are second on 19. Real Sociedad are top with 20 points.
"We had some very important players missing and it's not easy for any club to deal with the difficulties we are facing at the moment," said Madrid defender Nacho.
"But we showed character and played well, even though we're not happy that we couldn't get the three points."
Real's injury crisis led to Dominican forward Mariano making his first start since May 2019, when he scored twice in a 3-2 win over Villarreal, and he wasted little time in making his mark.
Villarreal protested the goal as the linesman had momentarily flagged for offside against Lucas Vazquez, who never made contact with the ball, and Dani Carvajal picked it up before crossing to Mariano.
Moreno was pleased with his side's reaction after a poor first half.
"We felt that we could have gone on to get the win, we had a few chances but the point is a good one considering how we started the game," he said.
"We failed to keep possession for long in the first half and struggled to make chances. But in the second half we changed that, we showed we're a team that loves to have the ball and we were the better side and should have won the game."