Japan kept alive their hopes of a quarterfinal spot at the Rugby World Cup with a superb 26-5 victory over Samoa on Saturday.

Played in front of a packed house at Stadium MK — a stadium record of 29,019 — the Brave Blossoms produced a disciplined, intelligent display of rugby to stop the Pacific islanders in their tracks.

"I'm very proud of the boys, but we have still got another game to go," Japan captain Michael Leitch said. "It was always going to be physical, we knew that, but we knew if we just kept at it and just kept chopping them down...and in the end I think our fitness showed."

"It (the next game against the United States) is another tough match. We've got another week's prep and we will just take all the positives from this game and just keep it on. The boys have pulled up alright and we have got another six days prep so we should be (alright) and are looking forward to it."

Whether the result will be enough for Eddie Jones' team to make the quarterfinals — and they still need to beat the U.S. on Oct. 11 — will depend to a great extent on the result of the day's later game between South Africa and Scotland in Newcastle.

But once again Japan proved they are more than capable of beating the big boys of world rugby.

A day after New Zealand became the first team to qualify for the knockout stages by beating Georgia 43-10 in Pool C, Japan needed to start well and hope their fitness would see them through.

And they did just that with Ayumu Goromaru banging over a penalty in the seventh minute, though Japan would have preferred the five from his "try" in the corner that was disallowed for a forward pass.

While Japan were playing disciplined rugby, the Samoans were not, and Faifili Levave and Sakaria Taulafo were both sent to the bin for dangerous tackles in the space of three minutes.

And Japan made the most of their numerical advantage with the forwards shunting the Samoan pack at a rate of knots resulting in referee Craig Joubert awarding a penalty try.

Goromaru added the extras and it was 10-0 with 23 minutes on the clock.

The Samoans tried to hit back but they were met with impressive defense as Ryu Koliniasi Holani and Kotaro Matsushima led the way with some solid tackles.

Joubert was having trouble with the Samoan discipline at the offside line and yet another penalty saw Goromaru increase the lead in the 33rd minute, before Akihito Yamada lifted the roof off the stadium.

The wing showed some great footwork to go over in the corner despite having very little room to move in. Goromaru then added the conversion from the touchline as Japan went into the break leading 20-0.

Japan had 70 percent of possession in the first half and they needed to repeat that in the second if they were to hold on for the win.

They also needed to keep making their tackles and maintaining their discipline. And they did just that, despite having Yamada stretchered off in the 55th minute.

Man-of-the-match Goromaru added two more penalties and although Paul Perez crossed for a try for Samoa in the 64th minute, Japan held on despite ending the game with flanker Hendrik Tui on the wing, hooker Shota Horie on the flank and wing Karne Hesketh in the centers as injuries took their toll.