Coach Jamie Joseph says Japan will have the element of surprise against South Africa after he named his side for Sunday's Rugby World Cup quarter-final.

While the Springboks have picked a powerful pack and six forward replacements, Joseph believes his team's tactics are not so obvious.

"It is clear what South Africa are going to do," he said.

"What is not so clear is what we are going to do; that is what I am looking forward to."

Ryohei Yamanaka's inclusion at full-back in place of William Tupou is the only change to the starting XV that beat Scotland in their final Pool A game last weekend.

Wing Kotaro Matsushima, hooker Shota Horie, second row Luke Thompson, prop Keita Inagaki, fly-half Yu Tamura and captain Michael Leitch were all part of the squad that famously upset South Africa in the teams' pool-stage meeting in Brighton four years ago.

The relaxed mood in the Japan camp shows as hooker Horie beats Joseph in a game of rock paper scissor.

Joseph said his players' confidence at the tournament has grown so much through their four successive wins - including victories over Scotland and Ireland - that he has had less to do as they prepare for the last eight.

"The players have really taken over," he said. "It is a really good sign as a coach when you feel a little redundant because you know there is real belief in your team."

Japan: Yamanaka; Matsushima, Lafaele, Nakamura, Fukuoka; Tamura, Nagare; Inagaki, Horie, Koo, Thompson, Moore, Leitch (c), Labuschagne, Himeno.

Replacements: Sakate, Nakajima, Ai Valu, Van der Walt, Lelei Mafi, Tanaka, Matsuda, Lava Lemeki