Tokyo - South Africa will seek to run Japan's fleet-footed "Ferrari" wing pairing off the road in this weekend's Rugby World Cup quarter-final, assistant coach Mzwandile Stick said on Tuesday.

SIGN-UP | Sign up for Sport24's 'Rucking with Rob Houwing' newsletter!

Kenki Fukuoka and Kotaro Matsushima have been stand-out performers at the tournament, delighting home fans in scoring a hatful of tries thanks to Japan's open, running style of attacking rugby.

But Stick vowed that the electric duo would be on the Springbok radar for the last-eight clash in Tokyo on Sunday.

Japan coach and former All Black Jamie Joseph previously compared their two wingers to Ferraris, given their raw pace.

"We have to not allow those Ferraris to go to fifth gear or sixth gear!" joked Stick.

Japan defied pre-tournament odds to win all their games to finish top of Pool A ahead of Ireland, who play defending champions New Zealand on Saturday.

And Stick said South Africa would be sure to not underestimate the Japanese team.

"They are a proper side at the moment. We don't talk about a Tier Two side anymore, because they are ranked seventh," he said.

"Whatever surprises they throw at us on the day, we must make sure we can handle those.

"We are also proudly South African, and we have our strengths that we will focus on."

Japan's 28-21 victory over Scotland in their final pool game, in Yokohama on Sunday, demonstrated a game plan based on ball retention, precision and speed of play.

It made for a wonderful spectacle of running rugby that has had not just fans in Japan purring but also pundits worldwide.

"Japan are a very good side. All the country's excited and behind them and we've seen how much they have developed in the last couple of years," Stick said.

Japan famously beat South Africa 34-32 in pool play at the 2015 World Cup, considered to be one of the biggest upsets in the sport to date.

In their second-ever encounter, the Boks saw off Japan 41-7 in World Cup warm-up match.

"When we played them a few weeks back, it was a warm-up game, there was obviously less pressure for both sides," said centre Lukhanyo Am.

"We've seen how much they've grown over their last four games.

"Whichever team controls the pressure more comes out tops," said Am, who will have his hands full containing Japan's dangerous midfield combination of hard-hitting Ryoto Nakumura and deft playmaker Timothy Lafaele.

Stick said the way Japan were playing had the hallmark of a strong Kiwi-influenced backroom staff, calling out ex-All Black Tony Brown.

"We know the New Zealand philosophy about the game, and putting the ball through the hands," Stick said.

"So, we can expect something close to how the All Blacks are playing. But when I'm watching them, they remind me of Argentina.

"That is one side where if they have time, they can be dangerous.

"We must make sure we are at our best with our defensive systems, because they are very skilful and have quick players."