Liverpool meet their great rivals as Prem leaders and overwhelming favourites.
Mac Allister said: "We've been in a really good moment and the feeling in the squad has been super-positive.
"But as we always say, at a club like this there's no time to rest or get carried away with what's happened - you just have to try to win and think about the next game.
"We know that players who come into the side at the start or as substitutes are really important and if you want to win trophies, you need them. Of course, you don't want to be on the bench, but we know what every guy here, when he comes in, does his best for the team."
On Arne Slot's impact, Mac Allister also said: "It's been a good feeling from day one. From the very start we saw a little bit of the way he wanted us to play and as a group I think we really embraced it. We're all comfortable with the way he wants us to play, with the tactical ideas that he's brought with him. I think you can tell that we've very happy.
"It's not easy for a new coach to come in, especially after a legend like Jurgen Klopp who was here for so many years and won so many things. I'm happy for Arne and for the whole group because the truth is that we work very hard and we're doing so in a great way. So hopefully we can crown it by winning him a trophy or two."