Japan coach Jamie Joseph named his side Wednesday for what he described as a "must perform" rather than "must win" game against South Africa later this week, the Brave Blossoms' final warm-up before the Rugby World Cup kicks off this month.

Dismissing comparisons with the previous encounter between the two sides — famously won by Japan at the last World Cup — Joseph stressed Friday's encounter would be between "different teams, different coaches and different ideas...and if we perform we can create a winning opportunity."

Michael Leitch captains a Japan side that contains just six players who featured in the 34-32 win over the Springboks in Brighton, England, and one uncapped player in Takuya Kitade as the Brave Blossoms look to continue their good form of late.

However, Joseph is well aware victory in the Pacific Nations Cup and playing the Rugby Championship winners are two different kettles of fish.

"We are under no illusions how tough it will be," he said. "We understand we are playing probably the biggest pack in world rugby and that it will be physically very challenging. But it's the type of game we need going into a physical Rugby World Cup."

With that physicality in mind, Uwe Helu starts at lock alongside Luke Thompson behind a front row of Keita Inagaki, Atsushi Sakate and Koo Ji Won.

Sakate's start is in part due to a neck injury to Shota Horie, and his promotion sees Kitade named on the bench.

With Kazuki Himeno ruled out with an ankle injury, Leitch joins up with Pieter Labuschagne and Amanaki Lelei Mafi in an athletic and powerful back row that will need to be at its best to stop the Springbok pack bossing the breakdown.

"The players are elated that he has picked his strongest side," Joseph said referring to South Africa coach Rassie Erasmus, whose side shows just one change — the recall of captain Siya Kolisi — from the team that drew 16-16 with New Zealand in July, the same side the Springboks will face in their Pool B Rugby World Cup opener on Sept. 21.

In the backs, Kaito Shigeno and Yu Tamura will look to make the most of the ball the pack wins with Kenki Fukuoka and Kotaro Matsushima providing plenty of pace out wide.

Ryota Nakamura and Timothy Lafaele line up in the midfield with Will Tupou at fullback, with the latter expected to be on the receiving end of a number of kicks from Springbok halfbacks Faf de Klerk and Handre Pollard.

Alongside Kitade, Isileli Nakajima and Asaeli Ai Valu provide the front-row cover with James Moore and Yoshitaka Tokunaga the two other reserve forwards.

Yutaka Nagare, Rikiya Matsuda and Ataata Moeakiola are the backup backs as Joseph opts for the traditional 5:3 split, rather than adding an extra forward to help counter the Springbok's physical threat.

"It will be hot and humid and we are anticipating there will be a lot of handling mistakes because of the slippery ball," he said. "(Besides) we have bigger things to look at."

"Everyone (in the squad) will have represented their country in a big match, some more than others," Joseph said in explaining his selections. "This is the last page of preparation."

Japan kick off their Rugby World Cup campaign on Sept. 20 against Russia before they take on Ireland, Samoa and Scotland in Pool A.