Hours before their Group F opener, fans from both teams donned face paint, giant football hats and even some furry kiwi bird outfits.
"Hockey is more popular than football but now since Slovakia have qualified for the World Cup, it has picked up and there is a lot more support for our boys in South Africa," Richard Vesely - as cheerful as his surname means in Slovak - told Reuters.
In the blustery car park a few kilometres from the Royal Bafokeng stadium, some New Zealand fans were wearing All Blacks' rugby shirts and desperately trying to protect their barbecues from the winds with giant umbrellas.
"We're usually rugby fans," said Dean Anderson, one of those dressed as a fluffy kiwi.
"But we just love New Zealand. We're a sporting nation, we just love the flag," he added, his yellow felt beak bobbing up and down.
The players have been enjoying the unusual attention, with some Slovaks saying they hoped football could replace ice hockey as the country's top sport.
"During the qualification the stadium was almost always full so I think it's different," Slovakia midfielder Miroslav Stoch told Reuters. "It changed because ice hockey didn't do very well recently, didn't finish in the world championship in the highest positions.
"There used to be not a big interest in football, I think we've changed it and hopefully now football will be the number one sport - it's now maybe 50-50, it's getting better."
The majority of the fans heading to the stadium were decked out in South African colours and Stoch said last week that he did not expect too many Slovak fans to make the long trip over.
"It's too far, the flight tickets and hotels are really expensive," he said. "And Slovakia is not really a rich country but I'm sure there will be people from Slovakia, but not many."
World champions Italy and Paraguay, who drew 1-1 on Monday, are the other teams in the group.
