Manchester United manager Louis van Gaal was full of praise for the Liverpool support after his side's 2-0 defeat at Anfield.
The Red Devils disappointed on Thursday night as they struggled to cope with the pace and determination of Jurgen Klopp's side.
They meet against next week with the Reds strong favourites to qualify to the next round.
"I have to say that Liverpool have created an atmosphere that is fantastic," van Gaal said.
"They played very good; in the first half we could not cope with their pressure. Still, they have chances but David De Gea was fantastic.
"We [gave away] a penalty and it was a cheap penalty, I think. In the second half, we changed the shape and then we had much more contribution to the game, but we didn't create many chances.
"They scored another cheap goal, I think, and that's difficult because 2-0 is a very difficult result for us.
"I have seen that we did not cope with the high pressure of Liverpool. For me, it was a surprise that we did not cope with it because they did it in the same way as the home match this year that we played against them.
"First they provoked that we could play the ball from David De Gea to Daley Blind or Chris Smalling and after that they gave a lot of pressure and we did not cope with that.
"That has also raised the atmosphere inside the stadium. They also created big chances but we had a very good goalkeeper and he is also part of our squad and because of that we were in the match. Then we got a cheap penalty [against us] I think and that was 1-0.
"The referee cannot see that [Memphis's challenge which led to the penalty] because I think that he holds him outside the box, and then he [Clyne] is falling down.
"That's not because he is kicked by Memphis, but it's difficult, you cannot see that in one second. You have to be sharp when you give it; if it was outside or inside, I don't know exactly. It is then, for me, a cheap penalty, but they deserved the goal."