Pool B:Australia outhalf Stephen Larkham is in doubt for the rest of the World Cup after undergoing a second knee operation.

Larkham was hoping to play against Canada this weekend after making a swift recovery from surgery last week but suffered a setback at training on Monday.

Australia coach John Connolly said Larkham was taken to a Montpellier hospital for arthoscopic surgery after his right knee became infected.

"We hope to get him out (of the hospital) tomorrow. He definitely won't be considered for this weekend or the weekend after."

Larkham's latest setback means he will miss Australia's last Pool B match against Canada in Bordeaux on Saturday and the quarter-final against England or Tonga in Marseille a week later.

The earliest he might resume playing is in the semi-finals in Paris in mid-October, if Australia get that far and the injury heals.

"I've spoken to the medical staff and they really can't say when he'll be fit to play," Connolly said. "We know we won't have him for the quarter-final but if all goes well he may be available the following week."