With two wins from two games at the Singapore 7s, Samoa has made their fourth straight Cup quarterfinal at a World Rugby Sevens Series tournament.

They defeated Japan 57-5, and with New Zealand's win over Spain both the Manu and the All Black Sevens will advance from Pool D regardless of how their match at 10:16 pm Samoan time turns out.

A tournament ending injury to star forward Tofatu Solia forced a reshuffle for the Japan game, with Tomasi Alosio moving into the forwards, Tila Mealoi getting a starting playmaker role and Siaosi Asofolau activated as the injury reserve to take Mealoi's spot on the bench.

Despite this, Samoa started brightly, with a flowing move of passes and offloads immediately getting them just 10 metres from the tryline.

Winger John Vaili broke three tackles to score from the next phase and make it 5-0 with less than 45 seconds played.

Japan responded immediately, breaking from kickoff for a try to Taisei Hayashi from their own second phase of possession.

Captain David Afamasaga sold a dummy from halfback, stepping through the line and showing great pace to breakaway for his side's second try, which made it 12-5 with under three minutes left in the half.

The Manu 7s broke again through Alosio who went all the way to the five metre line.

He looked to have gotten isolated at the ruck, but Alamanda Motuga came from nowhere and made a tremendous cleanout to keep possession, allowing Afamasaga to pick the ball up and score his second.

It was Samoa's offload game that was killing Japan (5-0 in the first half), and gave them a 17-5 with a minute left in the half.

They weren't done yet, as a kick pass from Melani Matavao took a funny bounce into the grateful arms of Motuga, whose resulting try came as the hooter sounded.

Vaili used his 1.93 metre frame and reach to snatch a Japanese pass out of the air and run in an easy try early in the second period.

Mealoi was next to score after a poor Japan lineout fell into his hands and he made it 38-5 with four minutes left.

With the win secure, coach Sir Gordon Tietjens rolled out the substitutes, and Paul Scanlan got his first ever Series try after a perfectly placed grubber to the wing from Matavao.

Phillip Luki opened his own World Rugby Sevens Series account straight after, benefitting from a nice Johnny Samuelu offload.

Elisapeta Alofipo completed the rout, scoring with the final play after Japan couldn't secure the kickoff.

Samoa will likely face either Fiji or South Africa in a Cup quarterfinal tomorrow afternoon.