Atletico Madrid produced an outstanding first-half display of attacking football as they thrashed La Liga leaders Barcelona in the first leg of their Copa del Rey semi-final.

A bad night for the visitors also saw them denied a goal back in the second half when, after a record-equalling eight-minute check by the video assistant referee (VAR), Pau Cubarsi's strike was ruled out for offside.

This was the second time in as many years these two sides had met at this stage of the competition, with Barcelona winning last year on their way to lifting the trophy for a 32nd time.

But Diego Simeone's side gained revenge in emphatic fashion by putting four goals past them in an astonishing first half.

Atleti's opener set the tone for what was a disastrous evening for Barcelona as Eric Garcia's backpass to Joan Garcia rolled under the goalkeeper's foot and trickled into his own net.

The hosts doubled their lead in the 14th minute when the competition's top scorer this season, Antoine Griezmann, curled home a fine finish against his former club.

From then on, Atleti took command and looked capable of scoring with every attack.

Fermin Lopez did hit the woodwork for Barcelona, but that was a rare opportunity in the opening period as Atleti hunted for more goals.

They added a third in the 33rd minute when Giuliano Simeone broke down the right before passing to Julian Alvarez and the former Manchester City forward clipped the ball across to Ademola Lookman, who drove in his second goal in as many games for his new club.

Argentine Alvarez then ended his two-month, 11-match goal drought with an emphatic finish, thumping an unstoppable drive into the back of the net from distance in first-half added time.

More misfortune followed for the visitors, who thought they had a goal back in the second half when Cubarsi prodded in after being set up by Robert Lewandowski.

However, VAR promptly decided to review the incident, with the check lasting so long that the goalkeepers were thrown footballs to warm up with.

Eventually, it was disallowed for offside and the length of the check equalled the record set by the eight-minute VAR stoppage during Bournemouth's FA Cup fifth-round win against Wolves last season.

Garcia and Barcelona's night got even worse when the defender was sent off with five minutes left following a VAR review after he fouled Alex Baena as the substitute burst through towards goal.

The loss has left Barcelona with it all to do when they host the 10-time winners in the return leg on 3 March.