Bob Dwyer has lit a fuse ahead of the Pool A blockbuster between England and Australia at Twickenham on Saturday, the Rugby World Cup-winning Wallabies coach suggesting that match referee Romain Poite must watch closely the tactics of Joe Marler.

The scrum has been singled out as the most important part of the "biggest pool match in Rugby World Cup history", and both teams will want to be on top of the set-piece as England are likely to become the first home nation to fail to reach the knock-out stages if they lose while the Wallabies, if they lose, will face their own pressured week of introspection ahead of a do-or-die contest against Wales the week after.

The Wallabies' scrum has been viewed as its Achilles heel for many years, and long-held perceptions in the northern hemisphere are hard to change; Australia, despite the improvement shown under former Argentina captain Mario Ledesma, now have a scrum they believe can 'disintegrate'' England at the set-piece, but still pundits in Britain expected they will struggle.

England dominated Wales at the scrum, winning four penalties from the Dragons, and Marler was central to that strength. Dwyer said, however, that Marler dominated Tomas Francis with illegal tactics, writing in The Telegraph in London that England's loose-head had been getting away with illegal scrummaging for years. The 1991 Cup-winning coach accused the Marler of driving in from a 45-90 degree angle when the rules state props must drive straight in the scrum.

Not straight referee Brett McKay / courtesy Fox Sports

"So much of the scrum is based on perception,' Dwyer said in the Telegraph. "The English work on having a reputation for legal scrummaging while doing the opposite. If I was [current Australia coach] Michael Cheika, I would be asking the referee: 'is that [Marler angling in] allowed?'."

Another former Wallabies coach, Eddie Jones, meanwhile, said of the importance of the scrum in a question-and-answer interview with Sir Clive Woodward for the Daily Mail: "If the Australian scrum holds up - and the actual number of scrums in a game is a big factor here - I'm tipping Australia".

"If they win their share of ball, they have just a bit too much round the park. And I'd back whoever wins the pool to get all the way through to the final."

Dwyer is a long-standing critic of the England set-piece, telling ESPN after they had defeated Australia on the back of set-piece dominance at Twickenham that their "scrummaging was totally against the written letter of the law".

But he is not alone in his criticism of England's set-piece, with former South African referee Jonathan Kaplan tweeting during the Wales Test that he would "like to see if the England pack square on the loosehead side ... just the once" and ESPN columnist Brett McKay sparking social media with the hashtag "Scrumstraightjoe".

I'd like to see if the England pack is square on the loose head side ... just the once

— Jonathan Kaplan (@RefJK) September 26, 2015

@WorldRugby be strict on Joe Marler's scrum tactics #ScrumStraightJoe pic.twitter.com/EQQxwpc6mw

— deGranville (@PVilsoni) September 29, 2015

Dwyer turned the blowtorch on England's forward coach Graham Rowntree, while suggesting Mako Vunipola, another England loose-head, was also getting away with questionable tactics.

"It must be by design," he said. "Neither of them scrummage square. Both of them angle in. Invariably that is at 45 degrees, but sometimes that ends up being at 90 degrees. Then when I see the opposition being penalised, I find that extremely hard to understand."

Cheika and his scrum doctor, Ledesma, insist, meanwhile, that Australia's approach is pure and simple to scrum hard and straight and leave the rest up to the referees.

And Cheika wasn't for baiting by talk of England's scrum pushing the boundaries, saying that referees "prepare very well for the game".

"All we can do is stay as square as we possibly can and make the opposition make their play from there, and see what happens," he said. "That's very much our strategy. I don't think it is any secret. And also, put in massive amounts of weight. Really push hard. That's the way our scrum is set up. I am sure [England] will have a tactic ... they very much bullied us in the scrum before and I think they will try and do it again."