Liverpool boss Jurgen Klopp was baffled by Atletico Madrid's negative tactics at Anfield on Wednesday.
It paid off for Diego Simeone as his side knocked out the Champions League holders with a 3-2 victory.
And Klopp was clearly annoyed with the opposition's tactics when speaking after game.
He said: "I don't understand with the quality they have the football they play. They could play proper football but they stand deep and have counter attacks.
"We accept it of course but it doesn't feel right tonight. I realise I am a really bad loser, especially when the boys put such an effort in against world class players on the other side who defend with two rows of four.
"We know in the last two years we had some lucky moments in the Champions League, you have to, to reach two finals, but today it was everything was against us in the decisive moments."