Levante stunned Barcelona with a 2-1 win in the first leg of their last 16 tie in the Copa del Rey on Thursday evening.
Early goals from Erick Cabaco and Emmanuel Boateng sent the home fans into delirium before Philippe Coutinho's late penalty gave the visitors some hope.
The match got off to a flying start when Levante took a shock lead after just four minutes, as Erick Cabaco headed home from Ruben Rochina's free kick after some awful marking from the Barcelona defenders.
The hosts then deservedly doubled their lead with 18 minutes gone, as Boateng turned provider when his dinked pass allowed on-loan Real Madrid striker Borja Mayoral to fire across goal and into the back of the net.
Levante had goalkeeper Aitor Fernandez to thank for keeping them in the game as he brilliantly saved Malcom's chipped effort with an outstretched leg. Barcelona again came close to scoring just before half-time, but Aleña's deflected cross fizzed out of the onrushing Malcom's reach.
Levante had a chance to put the game to bed with an hour gone, but José Luis Morales could not keep his composure when one-on-one with Cillessen.
They were then punished for their wastefulness when Coutinho's late penalty offered the visitors a boost in morale heading into next week's second leg.
Check out our breakdown of the game below.
Key Talking Point
The Blaugrana will be shocked and disappointed by this unexpected defeat, but Levante deserve credit for a fine team performance.
Although Ernesto Valverde named a much-changed side owing to a number of injuries, too many of Barcelona's players let the game pass them by.
The main concern for Valverde, however, is that his side were once again defensively poor. This is something that has become a trend in 2018/19 as they have shipped 20 goals in their 18 La Liga fixtures.
Their fragility at the back was brutally exposed by Borja Mayoral, who had a number of fine chances throughout the contest. Indeed, the 21-year-old could have scored more were it not for a fine display from Jasper Cillessen.
Substitutes: Sergi Roberto (6), Lenglet (6).
STAR MAN - In what was a lacklustre team performance by the Catalan side, they had Cillessen to thank for keeping them in the game.
Cillessen's save from Mayoral's shot shortly before the interval may go down as the pivotal moment in the tie, for a third Levante goal surely would have killed the game off.
The Dutchman proved that he is a more than capable understudy to the first-choice Marc-André ter Stegen.
WORST PLAYER - Many of Barcelona's outfield players were anonymous and lacked any urgency despite going 2-0 early on.
Ousmane Dembélé's pace did pose problems for the Levante defence, but the Frenchman failed to capitalise on any of the numerous chances he had.
Overall, it was a disappointing display from Barcelona, their players bereft of the typical flair that is their usual trademark.
Barcelona will be looking to return to winning ways in their next fixture, which sees them host Eibar in La Liga on Sunday.
Levante, meanwhile, will be ecstatic to have snapped a four game winless streak. They travel to Atletico Madrid earlier on Sunday.
The second leg of this round of 16 tie takes place on Thursday 17 January.