The Reds will defend a 1-0 aggregate lead for the second-leg of their Champions League round 16 tie. However, PSG are regarded by many as the form team of Europe.
Slot said on Monday: "They've impressed me a lot. Before we played the game, I watched many games of theirs because we had a bit more time than normal and I was really impressed with the intensity they play at, the team cohesion, the rotations in midfield.
"They are such a complete team, such a well-managed team and I think we experienced this last Wednesday. Some people said we played poor, I don't agree – I think they played tremendously well. I don't think we've faced this season a team that combined that much quality with that much intensity. But I do think we can do better. I am not saying we played poor or not good at all, but we are a better team than we were last week and that's something we have to prove tomorrow with the help of our fans."
Asked if they must produce their best performance of the season to see off PSG, Slot agreed.
"Yes, I do think so because this is the most complete team we've faced so far. What I mean by complete – and OK, we've faced Arsenal and (Manchester) City and it's not that there are big margins – but the intensity they've played at combined with the quality they have... they have so much quality and a great, great, great manager.
"He lets the team play in a way that is not easy to play against his team; he brings the best out of every player and he brings an incredible work-rate into the team. That's why I think we have to be at our best tomorrow. But, for example, we didn't have ball possession at all at City away but at home we had a completely different performance against City than we did away."
Slot was also asked if he's allowed himself to dream of winning a Premier League, Champions League and Carabao Cup Treble. However, he insisted there's point to doing that.
"No. In a week like this, you don't dream at all. You just know you have to work really, really, really hard to prepare the team in the best possible way, and that's what I try to do for every single game. But if you had a game like we had last week, you feel like, 'Can I even go to sleep or do I have to watch even more?'
"No, I don't dream at all at the moment about this week. We are just very focused on what we need to do tomorrow. The week started off, in terms of a result, really well on Saturday beating Southampton and now we are looking forward to tomorrow, because I think everyone looks forward to a game of football like this – at Anfield, two great teams playing against each other."