Ruben Sobrino bundled home a dramatic last gasp winner with his stomach to earn Cadiz a remarkable 3-2 win over Atletico Madrid, piling the misery on the visitors in a harrowing week for Diego Simeone's team.
It looked like Joao Felix had salvaged the Rojiblancos a point from two goals down, with a stunning impact off the bench, forcing an own goal and scoring another effort himself, stemming the bleeding after their Champions League elimination on Wednesday.
However after the eight minutes of added time had already expired, Sobrino finished from close range to stun Atletico at the death.
Atletico were still stinging from their dramatic knock-out on Wednesday, with Yannick Carrasco's last gasp penalty miss sealing their fate, and Cadiz took immediate advantage.
Theo Bongonda caught Simeone's side cold at the Nuevo Mirandilla with a goal just 27 seconds into the game, firing Pacha Espino's cut-back past Jan Oblak.
Alex Fernandez doubled Cadiz's lead with a well-taken strike in the 81st minute, before Luis Hernandez's own goal gave Atletico hope.
Then Felix, Atletico's record signing, slammed home from the edge of the box to level with two minutes remaining, which looked like it would salvage his team a point, before Sobrino's late strike.
Atletico remain provisionally third, although they can be overtaken by Real Sociedad or Real Betis, who face each other on Sunday, while Cadiz climb to 18th.
"Many times we have won in stoppage time, today, unfortunately, this happened to us," said Atletico midfielder Rodrigo de Paul.
"The (fans) know that this team gives everything, we gave everything today, we have to thank them because they are always with us."
ATLETICO DOUBTS
There are more doubts around Simeone's tenure than at any other point during his 11-year spell in charge of Atletico, during which he led the team to league titles in 2014 and 2021.
After conceding early to Bondonga, Alvaro Morata limped off for Matheus Cunha in the early stages after he had his foot stepped on by Cadiz defender Momo Mbaye, a worry not only for Atletico but also for Spain with the World Cup approaching.
De Paul fired narrowly off-target for Atletico, while at the other end Cadiz had a chance to double their lead before halftime but Oblak was quick off his line to deny Ruben Sobrino.
It looked like Alex Fernandez, brother of Real Madrid defender Nacho Fernandez, had sealed a surprise win for Cadiz, but there were more fireworks in store before the hosts could chalk up the three points.
Felix proved a personal point even as his team fell short in the end, with his bicycle kick accidentally powered into his own net by Hernandez.
Then the Portuguese striker, who has not earned a regular start for his club despite signing for 126 million euros (125.6 million dollars) in 2019 from Benfica, drilled past Jeremias Ledesma to level.
A point would still have been a disappointing outcome for Atletico, but after Sobrino's late strike, one they wish they could have settled for.
"I don't even know (how I scored it)," said Sobrino.
"It was a cross that was easy for the defender, he didn't clear it and when I saw it I hit it with my waist. It's the fruit of great work today."