The Brave Blossoms were on top of things in Toulouse and prevailed with three tries by Pieter Labuschagne, Michael Leitch, Kazuki Himeno and 13 points from the boot of Rikiya Matsuda.

Samoa had Ben Lam red-carded early in the second half and that helped Japan even though the Pacific side mounted a late comeback with a penalty and a Christian Leali'ifano converted try.

The result left Japan in second place on nine points, three ahead of third-placed Samoa. England, on 14 points, qualified for the last eight as Pool D winners.

Argentina take on Chile on Saturday and a bonus win would put them level with Japan ahead of their clash next week.

"That's our Grand Final, isn't it? We have got an opportunity to play a tier one team we have played a few times before," Japan coach Jamie Joseph said.

"All the guys are going to be really excited for that - it is a big game for us."

Argentina won their last encounter 54-20 in 2016 and their only World Cup meeting, 33-12, back in 1999, but Japan have since improved while the Pumas have been struggling recently.

To get there, Japan were made to work hard by Samoa, whose physical capacities pushed the Asian side to the limit.

"It was a really tough game and we had to work bloody hard to get the win. Hats off to the Samoan boys – they really took it to us,” Joseph said, praising his team's defence.

"They are big fellas aren’t they? They got on top of us at times and we had to really keep at it for the whole game," he added.

"The commitment was certainly there but there were one or two things to work on for next week."