Head coach Jamie Joseph's evolution in delegating and becoming a better communicator is a major reason why the Japanese are a win away from reaching the Rugby World Cup quarterfinals, forwards coach Shin Hasegawa said on Monday.

The Brave Blossoms will qualify for the last eight for the second successive time under Joseph if they beat Argentina in Nantes on Sunday in their winner-takes-all final Pool D match.

Both Japan and the Argentinians are level on nine points with England already guaranteed of topping the pool.