Ten-man Atletico Madrid were handed a humbling first defeat of the new LaLiga season in a dismal display at Celta Vigo, going down 2-0 at the Balaidos.
Maxi Gomez netted the opener in the 46th minute and then created the second for Iago Aspas in the 52nd as Atleti failed to recover from a poor first half in which they lacked cutting edge up front.
Antoine Griezmann sought to inspire his side, but a fightback never looked likely for Diego Simeone's men, who were tipped to put up a decent fight for the title.
Indeed, things went from bad to worse for Atleti as Stefan Savic saw red with 20 minutes remaining, although Gustavo Cabral was harshly denied a third by a marginal offside call after a VAR consultation.
After an open yet uneventful first 25 minutes in which the two sides took turns to counter, Griezmann was inches from firing Atleti in front as a 20-yard drive crept wide.
There was little incident of note in the remainder of a sweltering first half, but Celta took just 42 seconds to break the deadlock following the restart.
Gomez pounced on Diego Godin's slip to hammer low into the net and Atleti were quickly stunned by a second blow, the first goalscorer turning creator with a lovely delivery onto Aspas' head.
Savic was then dismissed for a second yellow card as he handled the ball to concede a free-kick from which Cabral thought he had added a third, before a lengthy VAR delay saw the defender judged offside.
What it means: Sloppy Atleti already slacking
The visitors' disappointing lack of cutting edge in the first half made the lapses early in the second all the more costly. With just four points from three matches, an Atleti side that looked primed for another LaLiga challenge are well off the pace already. There is work to do for Simeone.
Pat on the back: Maxi pounces on miserable mistake
Celta scarcely had a sniff in the first half, but Gomez turned the game in the space of little over five minutes. The finish for the first goal was clinical and the assist for the second was more impressive still, finding space inside on the right and picking out Aspas with a gorgeous cross.
Boot up the backside: Costa firing blanks again
Diego Costa is now goalless in 12 LaLiga games and, given that awful run, his aimless display was of more concern than an uncharacteristic Godin error. The Spain forward offered little in the way of either presence or goal threat, too often leaving Griezmann to work the Celta back-line alone.
Atleti will have to wait for their opportunity to bounce back. The international break means it is a fortnight before they face Eibar in their next match. Celta travel to Girona two days later.