And he insists his side will show no fear as they defend their 2-0 lead at Old Trafford.
The Kop boss insists his players are not treating the second leg of the last-16 clash as a holiday despite a convincing win in the first game.
Klopp said: “This is the third time we have played against Man United. We have always been in the game. That is an important sign for us.
“The world doesn’t change overnight. It is absolutely clear there is a chance for Man United, 100 per cent, that is football. Everything can happen.
“But we know that we know how to play them. That is the truth. That doesn’t mean it is easy for us. We have to work really hard.
“We have to be concentrated, be brave and aggressive in a legal way. That is what is clear.”
When asked if there is anything that worried him about tomorrow night’s clash Klopp added: “Not not really, no. It’s football. The ball is round? Right?