The Dons on Tuesday claimed a 2-1 win at Fir Park to advance to the fifth round of the William Hill Scottish Cup and on Saturday turn their attentions to SPL duty at Pittodrie, where they lie fifth and have just two league wins from eight matches.
Magennis said: "It's going to be a big game because we don't want to be in and amongst it in the top six, we want to break away (into the) top two or top three. Three points on Saturday will put us right up there.
"They (Kilmarnock) can play great football, that's if you let them play. We know if we pressure them the way the gaffer tells us and if we don't let them play we'll be all right.
"I'm expecting a high-tempo game. They're known for passing the ball about and we're known for that this season as well.
"Whichever team is the bravest and whoever is looking for the ball is going to come out on top."