(BSS/AFP) - Barcelona coach Hansi Flick said his players did not work as a team and were taught a lesson in the first half of the 4-0 Copa del Rey semi-final first leg defeat by Atletico Madrid on Thursday.

The holders and La Liga leaders were crushed at Atletico`s Metropolitano stadium as Diego Simeone`s side ran riot with four goals before the break.

"We didn`t play well in the first half as a team, we didn`t play like a team," Flick told reporters.

"The distance between everyone was too long and we didn`t press how we wanted."

The German coach said his side were taught a lesson which could come in handy later in the campaign.

"In the first 45 minutes we were handed a big lesson. Sometimes it`s good to get (that) in the right moment, maybe today is the right moment," continued Flick.

"The second half was much better and we have one game more and we will fight (to win) that."

Barca`s Pau Cubarsi had a goal controversially ruled out for offside in the second half, with the VAR review taking a long time and it not being made clear who was offside at which point for spectators in the stadium or watching on television.

"It`s a mess, it`s a mess like that, and then they have to wait I don`t know how many minutes, was it seven minutes? Oh come on," complained Flick.

"They found something in the seven minutes? Okay. For me, when I saw this situation it was clear (there was) no offside, but at the end maybe they could see something different, but tell us.

"There was no communication and this is so bad here."