New Zealand are faced with a must-win scenario at McLean Park after they lost their opening 50-over match of the three-game series in Wellington on Saturday.
South Africa beat the home side with relative ease during the weekend, but the Kiwis have a strong record in Napier where they have won 21 of their 35 one-day games.
Stand-in New Zealand captain McCullum, who averages 30.73 from 22 games against South Africa during his 199-ODI career, said his side weren't in awe of the Proteas.
"There's a lot of stuff that needs to go in to the mix for tomorrow, but I think from an overall perspective we are excited about the opportunity we've got tomorrow,'' he said yesterday.
"We are not afraid of what's in front of us. We don't fear South Africa. We know they're a very good team. We know that we have to stand up to them, play exceptional cricket to beat them, but we don't think we are that far away.''
The world rankings would beg to differ though, with New Zealand seventh on the pecking order to South Africa's No 2 spot.
But in their own conditions New Zealand thrive and the short square boundaries of McLean Park could suit the Kiwi batsmen.
South African captain AB de Villiers hinted that with a rock-hard pitch awaiting them, his pacemen such as Morne Morkel might look to take advantage of the surface and extract extra bounce.
When McCullum was told of the potential plan from the visitors to dig it in short, he welcomed it.
"I think they will go short, which presents us with an opportunity as well ... If we are smart and we take the options on offer as well, then we may be able to expose their want to go short at us. I'll be asking our bowlers to pitch it up a bit fuller and get them to play down the ground.''
New Zealand have dropped Michael Bates and Doug Bracewell out of their 12 from Saturday's game and replaced them with Tarun Nethula and Andy McKay.
McCullum said he would make a call on who would carry the drinks once the conditions had been assessed.
Tom Latham has also joined the squad as cover for Jesse Ryder but the big Wellingtonian is expected to play as he manages his troublesome calf.
Napier has been known for high-scoring encounters in recent years and McCullum said he expected a score of around 300 to be par, although he didn't know if chasing or batting first was the way to go.
The home side will need a big contribution from their consistent top order and they have to make more than the 253-9 they mustered on Saturday.
South Africa are likely to keep the same XI that disposed of New Zealand in game one, and de Villiers said the pitch looked like a ripper.
"It's rock hard, I walked on it tapping it and by a long way it's the hardest wicket we've played on. All fast bowlers enjoy a bit of bounce and some batters too. I personally enjoy wickets like that to bat on. I know a guy like Morne Morkel enjoys it too.''
Graeme Smith (arm) and Hashim Amla (head cold) were under an injury cloud today (tues), but de Villiers expected both of his openers to play.
Today's game starts at 2pm.
