Tokyo - England take on Australia and defending champions New Zealand play Ireland as the Rugby World Cup in Japan suddenly gets serious in the quarter-finals on Saturday - with reputations and coaches' futures at stake.

For all four coaches, Saturday's games could be their last in charge as four years of investment and planning comes down to 80 minutes in Oita and Tokyo.

The first World Cup in Asia has already seen 37 games since it kicked off a month ago, with three scrapped after a powerful typhoon hit Japan in the final weekend of the pool phase, leaving scores of people dead.

England and New Zealand both had their final pool games cancelled, giving them an extra week to prepare for the last eight -- but possibly also depriving them of match sharpness.

New Zealand's Steve Hansen and Ireland's Joe Schmidt are both stepping down after the World Cup, while Australia coach Michael Cheika's contract is up and England's Eddie Jones is widely expected to move on.

Wales play France and hosts Japan, the tournament's surprise package, are against South Africa in Sunday's quarter-finals, also in Oita and Tokyo respectively.

England's clash with old rivals Australia looks the tighter of Saturday's two games, and features an intriguing match-up between two coaches who played together at club level.

Jones's decision to drop fly-half George Ford caused great debate as he reverted to his Six Nations combination of Owen Farrell at pivot with Manu Tuilagi and a fit-again Henry Slade in the centres.

Cheika, who packed down with Jones at Sydney's Randwick club, also sprung a surprise when he named 19-year-old Jordan Petaia, Australia's youngest World Cup player, at outside centre in just his third Test.

With both teams featuring imposing ball-carriers, the midfield promises to be one of the main battlegrounds along with the scrum, where Australia are vastly improved in recent times.

There will also be much focus on the breakdown where Australia's much vaunted 'Pooper' combination of David Pocock and Michael Hooper will come up against England flankers Tom Curry and Sam Underhill, dubbed the "kamikaze kids".

England number eight Billy Vunipola, back from an ankle injury, will play alongside his brother, prop forward Mako, who is making his first start since May following a hamstring problem.

"I think I shocked a few of the boys," Billy Vunipola said.

"Wednesday is our biggest training day, and I said 'Lads, this could be our last session'. I had a few stares from the lads and they just all laughed it off, but I was, like, I am being serious, if we don't turn up, we are going home."

The All Blacks, going for their third straight title, start as firm favourites against an Ireland team who are yet to hit their stride in Japan.

However, both teams are mindful of the fact that Ireland have won two of their last three games against the world's top-ranked side, after 2016's 40-29 win in Chicago and a 16-9 victory in Dublin last year.

Conor Murray and World Player of the Year Johnny Sexton, one of the world's most settled and formidable half-back pairings, lead Irish hopes against a youthful New Zealand back line.

Beauden Barrett remains at fullback behind fly-half Richie Mo'unga in Hansen's double playmaker ploy, while Jack Goodhue comes into the centres and Sevu Reece and George Bridge are on the wings.

"It's a little bit surreal, it's a little bit 'I can't believe it's finally here'. This time four years ago I was a spectator like you guys and it's not a great place to be," said Sexton, who missed Ireland's 2015 quarter-final - a 43-20 defeat to Argentina -- with a groin strain.

"So I'm really looking forward to going out there on the biggest stage and trying to show what we can do against the best team in the world, a team that hasn't lost for two World Cups."

SATURDAY, OCTOBER 19

England v Australia, Oita - 09:15

New Zealand v Ireland, Tokyo - 12:15

SUNDAY, OCTOBER 20

Wales v France, Oita - 09:15

Japan v South Africa, Tokyo - 12:15