Wallabies' Carter Gordon sent home early with knee injury

The Wallabies' wretched World Cup just goes from bad to worse with Carter Gordon and Nick Frost ruled out for the remainder of the tournament through injury.

Lock Frost suffered a right knee joint injury in the victory over Portugal on Sunday, with scans showing he won't be available for selection in the unlikely event Australia make the quarter-finals.

The 22-year-old Gordon picked up his knee cartilage injury at training last week and is flying back to Australia for treatment as soon as possible, Rugby Australia announced on Wednesday.

The only consolation for both players is that they would have been hugely unlikely to have featured in the knockout stages anyway, with Fiji, their pool conquerors, prohibitive favourites to qualify at Australia's expense by beating Portugal this Sunday (Monday AEDT) in Toulouse.

Wallabies head coach Eddie Jones said in a statement from RA: "We're disappointed for Nick and Carter that their seasons have ended through injury."

"Nick showed great courage to play through significant discomfort against Portugal, while Carter has earned valuable experience during his first year as a Test player.

"We wish both of them a quick and successful recovery and to watching them continue to improve during Super Rugby Pacific next year."

For the luckless Gordon, it's the end of an ill-starred campaign after he was effectively singled out by Jones to be the poster boy for his youthful selection gamble in France as the side's only specialist five-eighth, with elder, more experienced pivots like Quade Cooper and Bernard Foley left out the squad.

It's a gamble that singularly backfired, with Gordon, after struggling in the early matches and misfiring from the kicking tee, hooked after 50 minutes in the loss to Fiji and then dumped before the must-win Wales match, which Australia lost 40-6.

Gordon was then a last-minute withdrawal from the team to play Portugal in Saint-Etienne last weekend after picking up his injury.

Utility Ben Donaldson was promoted to No.10 but there's now no cover for him in that position, demonstrating the folly of Jones's original selection.