Liverpool have been knocked out of the Champions League after being beaten by Atletico Madrid.
The Reds went into the game with work to do after losing 1-0 in Madrid three weeks ago.
And they took the lead on the night when Georginio Wijnaldum headed home just before half-time.
They had multiple chances to win the tie in the 90 minutes but Jan Oblak made several crucial saves to send the game into extra-time.
The Reds took the lead for the first time in the tie when Roberto Firmino netted in the 94th minute.
It was a disappointing night for Liverpool, who had so many chances to win but simply could not take their opportunities.
Diego Simeone's side were up against it for most of the game and defended for their lives at times, but found the goals they needed to progress.
But Klopp was not happy with the Spanish side's tactics after the game.
He criticised Atletico's tactics and lamented them for 'not playing proper football'.
"I don't understand, with the quality that they have, that they play this kind of football. I don't understand," he said.
"The winner is always right. But when I see players like Koke, Saul, Llorente... the players they have, they could play proper football.
"But they play deep in their half and have counter-attacks."
You can watch his post-match interview below: (he made these comments at 2:38)
Klopp doesn't take losing well at all, does he?
Despite criticising Siemone's tactics, he did at least congratulate them shortly after for going through.
Simeone was asked about Klopp's comments in his own post-match interview.
When asked how his side plays, he simply replied, per Miguel Delaney: "To win. With all our soul."
Given the heart both he and his side showed on Wednesday night, he's certainly not wrong.
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