The Rugby World Cup may be over for Wallabies utility back Matt Giteau who damaged his ankle late in Australia's 33-16 win in their quarter-final against Scotland on Saturday night.

Giteau limped off the Suncorp Stadium field in the 73rd minute after his ankle twisted beneath him as he was tackled.

The 21-year-old appeared to be in a lot of pain and Wallabies coach Eddie Jones confirmed he had been taken away for an MRI scan.

"We'll know more in the morning but certainly it looks pretty serious," Jones said.

Giteau replaced five-eighth Stephen Larkham in the 53rd minute and continued the impressive form which has marked him as one of finds of the World Cup.

He suffered a fractured knee late in the Super 12, which ruled him out rugby until midway through Australia's Tri-Nations campaign.

Blindside flanker George Smith was forced off at halftime with a shoulder injury which Jones said appeared minor, however he would be further assessed in the next few days before Australia's semi-final showdown with New Zealand in Sydney next Saturday.

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