Rugby World Cup 2019: Wallabies set to drop James O'Connor against England

Michael Cheika is poised to announce one of the biggest gambles of his Wallabies coaching career by fielding teenager Jordan Petaia in the midfield for their World Cup quarter-final against England.

Media sources have reported that Cheika has dumped outside centre James O'Connor and will play 19-year-old Petaia in that position in Oita on Saturday, for the first time in his short test career.

Petaia became Australia's youngest World Cup player, when he made an excellent test debut against Uruguay on the left wing two weeks ago.

He was switched to the right wing for his second appearance against Georgia last week, where he had a quiet outing.

Cheika has attracted criticism for experimenting through the pool stage, but this switch would come without any sort of trial run.

A hamstring niggle meant the youngster was unavailable to face Fiji and Wales in the first two pool games.

Queensland Reds back Petaia is regarded as one of the country's brightest attacking talents, but has barely played in 2019, after seriously injuring his foot in the second round of Super Rugby on March 2.

He still wasn't fit enough for the Rugby Championship programme and the hamstring issue sidelined him from last month's warm-up test against Samoa.

O'Connor impressed in Australia's win over Fiji in Sapporo a month ago, but appears to have paid for two ineffectual outings since.

rwc playoffs
Photo credit: Newshub.

While Cheika looks set to name a predictable forward pack, other surprising backline changes appear on the cards for the test, which would bring the curtain down on his Wallabies career, if they lose.

The coach looks set to field centurion Will Genia at halfback, after favouring Nic White through most of 2019.

Kurtley Beale is poised to start at fullback and Reece Hodge on the wing, leaving no room for in-form Dane Haylett-Petty.

Beale is believed to have passed his concussion protocol, after being forced off against Georgia by a heavy head knock.

Essential Guide to 2019 Rugby World Cup

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The ninth Rugby World Cup kicks off on September 20 in Japan - the first time it has been hosted in Asia.

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AAP