Ngongotaha had no problem in front of goal last season - netting 111 goals while dropping just four points on their way to the league title.
But Davis stressed Northern League football was a "whole new ball game".
"It's very important to pick up points and we need them now, this isn't a situation we're used to," Davis said.
"We all know where we fell down against Papatoetoe. We didn't find the back of the net. We must find the back of the net, we have the quality in front of goal - it just needs a bit more composure and cool heads all round.
"We've no idea what Mangere will be like but that isn't an issue - we just need to look at ourselves and what we can do."
Ngongotaha will have to make some adjustments with defensive midfielder Josh Haua unavailable due to suspension after being sent off against Papatoetoe and striker and main talisman Mitchell Miller also unavailable for the next two weeks.
Midfielder Alan Fergusson returns to the fold after a head collision during the Papatoetoe game and French right winger Alexis Pinto is set to step up to the mark for his new club.
"We'll have to shuffle around a bit. It won't change our game plan too much though or our formation. It gives the chance for a couple of players to push up like Alexis. He's shown promise in pre-season."
Davis added the side would need to push further up the field on attack.
"Our defence was very strong in our last match - I want to see that again. We need to push higher up the pitch though - that's going to help us create chances.
Northern League, division two fixtures:
Saturday
Onehunga Mangere AFC v Ngongotaha AFC, Mangere Domain 1, kick-off 2.45pm.
Northland FC v Takapuna AFC, Tikipunga Park 1, kick-off 3pm.
Papatoetoe AFC v Mangere Utd, Murdoch Park 1, kick-off 3pm.
Albany Utd v Claudelands Rovers AFC, QBE Stadium 4 FT, kick-off 3pm.
Fencibles Utd v Te Atatu AFC, Riverhills Park 1, kick-off 3pm.
Waiheke Utd AFC v Papakura City, Onetangi Sports Complex 2, Sunday, kick-off 2.45pm.