The chances of veteran Wallaby first five Stephen Larkham playing again at the World Cup are looking slimmer by the day after he spent Monday, Tuesday and Wednesday in a Montpellier hospital recovering from his second knee operation in France.

While he remains optimistic about taking the field for the Australians in a possible semifinal clash with the All Blacks, Larkham faces a huge race against time to be ready by that stage.

"I do feel a lot better than yesterday, and the swelling has come down a bit," Larkham told the Sydney Morning Herald on Thursday.

The 33-year-old can't even walk without crutches yet and doctors say it could take at least four more days before they are able to determine his immediate rugby future.

"I am hoping everything will be cleared out by Monday, and I am certainly hoping of playing again in this World Cup," Larkham said.

Larkham was released from hospital on Thursday and will travel with the Wallabies to Bordeaux for their clash against Canada.

"Thankfully, the infection was on the outside of the knee, and not within the knee joint. Our team doctor (Martin Raftery) definitely made the right decision of me returning to hospital as soon as possible, and we were able to get at it early enough. So I am feeling lot more happier now."

"We've got to give him time," said assistant coach Scott Johnson.

"You owe it to the team and you owe it to Stephen [Larkham] to give him as much chance as we can. Now that we're through [to the quarter-finals], we've bought ourselves some time.

"It is always discouraging when a player gets some issues he didn't expect. It is his swan song, and he doesn't want to cut it short," added Johnson.

"The first job is to get that swelling down. If we can get that down pretty quickly, we are going to be on target. If we fail to get that down, or he doesn't respond, then it is going to be slower.

"In a week's time, we'll be able to give a much clearer picture of where we are heading.