Liverpool won 3-0, with Luis Diaz scoring twice and Mohamed Salah also netting.
Asked if the match could've gone better, Slot said: "No, no I don’t. I think everything you want to see as a manager you saw in this game. So, there were difficult moments for us – I think United started really well and we conceded one or two corner kicks in that moment.
"But we fought ourselves through those moments and then we got the disallowed goal but there was no negative reaction at all, we just kept on playing afterwards: scoring three, we could have scored more, two important saves from Ali in the second half. So, everything was there and maybe the one that was most important is that the work-rate was incredible by all of them without the ball, and that makes it a very positive day today.
"I normally don’t use the word ‘proud’ but what I think we did very well in all three games is, like I just mentioned, the work-rate without the ball. So, we try to press the opponent as high as we can but if they play through or over our press, I see everybody working really hard to make sure we don’t need Ali and sometimes we do and then it’s a good thing that we have a real good goalkeeper.
"What impressed me most today was the way we played with the ball because I know what we can do without the ball, but the way we played with the ball was I think also very good today.
"It was special to be involved in this game and it’s only special if you win it, and that’s what we did. So, really pleased that we won it but maybe even more with the game and how we did it today."