LONDON (AP) — With every match on Japan's Rugby World Cup journey, millions more people tune in back home to follow the Brave Blossoms.

Imagine where it could lead if Japan reaches the quarterfinals.

To get through, Japan needs to beat last-place United States in Pool B on Sunday night in the very last match of the pool stage, while relying on Samoa to beat Scotland on Saturday.

"This game for us will be the most difficult and most important," Japan captain Michael Leitch said. "We have to get ourselves right mentally. We can't worry about Saturday's result."

Even if coach Eddie Jones' players don't progress to the knockout stage, they're among the stars of the World Cup.

It all started on the first weekend of the tournament, on a sunny afternoon on the English south coast, when Japan stunned two-time champion South Africa with a 34-32 win in Brighton. It turned the form-guide upside down.

Japan had previously only won one World Cup match. Now they're aiming for three in four matches.

Suddenly, rugby, a niche sport in a country where baseball, soccer and sumo wrestling dominate, is in vogue.

Last Saturday, 25 million people watched on TV as Japan beat Samoa 26-5.

That beat the previous national TV audience record for a Rugby World Cup match — set by the French for their team's loss to England in the 2007 semifinals — by more than four million.

If Samoa does Japan a favor and beats the Scots, then the TV viewing record could well be eclipsed on Sunday night — even if the 8 p.m. kick off local time in Gloucester is 4 a.m. in Tokyo.

Here's a look at Sunday's four games at the Rugby World Cup:

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ARGENTINA vs. NAMIBIA (2-0, both in RWC), Leicester, 1100 GMT

Argentina has already qualified for the quarterfinals, courtesy of New Zealand's win over Tonga on Friday, and selected a team with that in mind.

From the XV that started the 45-16 win here over Tonga last week, the Pumas retained only lock Guido Petti, flanker Pablo Matera, scrumhalf Martin Landajo, who will be captain, and winger Matias Moroni.

It is the youngest and most inexperienced Pumas lineup at a Rugby World Cup in 16 years, and the start for center Juan Pablo Socino ensures every Puma in the squad will have played at least once in the pool stage.

Namibia earned its first ever competition point at the World Cup from a 17-16 loss to Georgia on Wednesday, and coach Phil Davies said he hopes his team can show the same doggedness.

"If we go out with that guts, character, determination, anything can happen," Davies said after announcing 11 changes to his lineup. Flanker Jacques Burger retired after he was concussed against Georgia.

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ITALY vs. ROMANIA (22-3-16 overall, 1-0 in RWC), Exeter, 1330 GMT

Romania warmed up for this by coming back to beat Canada 17-15 after trailing 15-0, the biggest comeback in tournament history.

A win for either team will secure third place in Pool D and an automatic berth in the 2019 World Cup in Japan.

Romania coach Lynn Howells must do it without influential No. 8 Mihai Macovei, who scored both tries against Canada but was later suspended for two weeks for a dangerous tackle.

The Italians, too, are without talismanic captain Sergio Parisse, who played in the 16-9 loss to Ireland but has been ruled out with a lingering calf injury.

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FRANCE vs. IRELAND (56-7-31, 3-0 in RWC), Cardiff, 1545 GMT

France coach Saint-Andre has extra motivation for the Pool D first-place decider.

Not only would victory in Cardiff be his first in five matches against the Irish, it would mean avoiding defending champion New Zealand in the quarterfinals.

France has been building slowly and showed glimpses of its attacking form in the 41-18 win over Canada last Thursday.

Six Nations champion Ireland seemed to go backwards last Sunday when grinding out a 16-9 win against Italy.

Both teams are level on 14 points.

Although Ireland has the recent edge on Saint-Andre's team in Six Nations, the French often save their best for the World Cup.

"My players are desperate to play in this match," France coach Philippe Saint-Andre said Friday. "They've had it in mind for a very long time."

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UNITED STATES vs. JAPAN (13-1-8, 2-0 in RWC), Gloucester, 2000 GMT

Japan has already proved a point at the Rugby World Cup. The United States has yet to notch one in the pool standings.

Having beaten South Africa and Samoa, the Brave Blossoms have a shot at the quarterfinals, providing Samoa beats Scotland on Saturday.

The Eagles are coming off a 64-0 loss to South Africa, the biggest margin of the tournament, but have an almost entirely new starting XV.

"We realize the U.S. rested their best team on Wednesday and just announced their strongest side will play against us, which is exactly what we want," Japan coach Eddie Jones said.