Taking the game to the Reds, Atalanta emerged with a 3-0 away win to take to the return leg at home.
Post-game, Klopp told reporters: It's easy Atalanta are causing many teams problems with the way they defend.
Maybe I'm wrong but I cannot now remember situations where they outplayed us, it's just they won the ball and they went from there, so it's a good idea.
You need a lot of tactical discipline to do what they did. They play that man-marking over the whole pitch Ederson pressing whoever, Curtis (Jones) in our own box, stuff like that.
That was the reason why they won the game, because in these moments you just want to win the ball.
Man-marking is uncomfortable when you are not on top of your game. That's why so many teams play it again. But if you play, if you are in a better playing mood than we were tonight then you can cause massive problems but we didn't. So that's the reason.
They defended us and we didn't try it long enough to play, so then we just suffered from their way, the way they defended. That's pretty much the explanation, that's the one point."