Japan are taking everything in their stride as they look to continue their Rugby World Cup fairytale by sneaking into the quarter-finals.

Eddie Jones and Japan are the feel-good story of the 2015 World Cup after producing one of the biggest upsets in rugby union history to stun two-time champions South Africa in their opening tournament fixture last month.

That dramatic 34-32 victory, made possible by Karne Hesketh's try in the final minute, set the tone for Japan, who remain in contention for a last-eight berth in Pool B.

Japan, who will host the 2019 tournament, are third in the pool on eight points and must beat United States on Sunday, while hoping second-placed Scotland lose to Samoa 24 hours earlier in Newcastle.

However, captain Michael Leitch and Co. are not focused on results elsewhere as they prepare to lock horns with last-placed USA in Gloucester.

"This week's game for us will be the most difficult and most important. We've been picking it up since Monday," said Leitch.

"The USA are a much different team here compared to the one from the PNC [Pacific Nations Cup].

"We have to get ourselves right mentally. We can't worry about Saturday's result [between Samoa and Scotland].

"America are an emotional team. If you've seen them play at this World Cup they've been playing well. You can tell they are fired up by watching them sing the national anthem. Pressuring them on set-pieces will be crucial."

Japan have made four changes for the final pool fixture, with 35-year-old former Australia rugby league international Craig Wing set to become the country's oldest World Cup debutant.

No less than 13 changes have been made to USA's starting line-up.

Samu Manoa and Zach Test are the only players to stay in the team as USA look to exit the tournament with a win under their belt.

USA coach Mike Tolkin said: "Every World Cup is important. It comes out as a cliché but we treat every World Cup game in the same way.

"They are games we want to win and prepare hard to win. We’ve gone head-to-head with them a few times in the last year or so.

"They have had success in this tournament, so finishing well against them will show what we are about in this tournament."