Atletico Madrid hammered Copa del Rey holders Barcelona 4-0 on Thursday in the first leg of their semifinal.
After an Eric Garcia own goal sent Diego Simeone's side ahead early on, Antoine Griezmann, Ademola Lookman and Julian Alvarez struck to give Atletico a landslide lead by half-time.
Barca defender Garcia was sent off in the final stages, with Atletico maintaining their significant advantage on the record 32-time winners, which they will take into the second leg at Camp Nou on March 3.
BIG WIN IN THE FIRST LEG!! pic.twitter.com/uVugkAPx9p
— Atlético de Madrid (@atletienglish) February 12, 2026
Both sides missed good chances in the second half, with Barca's Pau Cubarsi having a goal disallowed before Garcia was sent off in the final stages.
Atletico were able to preserve their significant advantage on the record 32-time winners, which they will take into the second leg at Camp Nou on March 3.
"In the first 45 minutes we got a great lesson for us. Sometimes it's good to get (that) in the right moment, maybe today is the right moment," Flick told reporters.
"The second half was much better and we have one game more and we will fight (to win) that."
Well off the pace in LaLiga and not showing the quality of a side likely to go deep in the Champions League, the Copa del Rey represents Atletico's best chance of silverware this season.
With that motivation in mind, the Rojiblancos conjured the best football of their season to completely dismantle the Spanish champions in the first half, as the fans lapped it up.
"I think our fans need these games, they've been coming for years, pushing, they're always there, they need big matches," said Simeone.
"We had a great first half, reading the game very well, we were very efficient and calm in the final third."
The hosts took the lead after seven minutes when Garcia's pass, on the uneven Metropolitano stadium pitch, bobbled towards Joan Garcia and then under the goalkeeper's foot and into the net.
Former Barca striker Griezmann slid home the second as Atletico breached the Catalans' high defensive line repeatedly, leaning on the pace of Giuliano Simeone and Lookman.
Fermin Lopez hit the crossbar for Barcelona but it was one-way traffic and Atletico nearly got a third when Alvarez's effort was cleared off the line by Jules Kounde.
Eventually Nigeria international Lookman steered home the third at the end of a fine team move, with overjoyed Atletico coach Simeone racing down the touchline in celebration.
ALVAREZ DROUGHT ENDS
Having spent much of the season demanding his team take their chances more clinically, all of the Argentine's dreams came true at once.
Alvarez, who had failed to score in his last 11 matches, ended his drought for Atletico's fourth, ramming home from just inside the area.
"We all know how important Julian is for us, he showed it last season," said Atletico midfielder Marcos Llorente.
"I'm really happy for his goal, I'm sure it will take a bit of the weight off."
Atletico goalkeeper Juan Musso saved well from Lopez to keep his clean sheet at the interval.
Barcelona thought they had pulled one back in the second half when Pau Cubarsi netted but it was controversially disallowed after a long VAR review for an apparent offside.
"I want to have the reason why it was offside," Flick told Movistar. "I don't know what they saw."
With a few minutes remaining the league leaders' night got even worse, when Eric Garcia was sent off for a foul on Alex Baena as he ran through.
Ferran Torres's poor pass sold his team-mate short and he clumsily felled the Atletico playmaker.
Alexander Sorloth and Torres spurned further chances at each end as the game kept its frantic pace until the end.
Flick said Atletico's players seemed more determined to win.
"When you saw the the players from Atletico they have more will, they have more hunger to score goals, and this is what what I want from the beginning from the first first minute, and in the first 45 minutes we we didn't show that," lamented the German coach.
On Wednesday Real Sociedad beat Athletic Bilbao 1-0 in the first leg of the other semi-final clash.