Wallabies teen in selection 'bombshell' for Rugby World Cup quarter-final

Michael Cheika has announced 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.

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.

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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 will 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 program and the hamstring issue sidelined him from last month's warmup 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.

More changes on the cards for Wallabies?

The coach handed centurion Will Genia halfback duties, having favoured Nic White through most of 2019.

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

Beale has passed his concussion protocol after being forced off against Georgia following a heavy head knock.