Atletico Madrid hammered Copa del Rey holders Barcelona 4-0 on Thursday in the first leg of their semi-final.

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.

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 La Liga 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. (AFP)