Having just emerged from the school of hard knocks, Berrick Barnes knows he'll be a marked man at the Rugby World Cup starting next month.

But the 25-year-old playmaker promised teammates he wouldn't let them down after edging out 92-Test stalwart Matt Giteau for a place in Australia's 30-man squad on Thursday.

Barnes' World Cup hopes looked in serious jeopardy when he sat out the final month of NSW's Super Rugby campaign with footballer's migraine following a spate of worrying head clashes.

He only confirmed his availability to coach Robbie Deans three weeks ago, but says four club games for Sydney University had restored his confidence to return to the frontline.

"No doubt they'll send cattle my way," Barnes said of opposition attacks likely to target Australia's headgear-wearing backline utility.

"But they send cattle at anyone that stands at 10, so I won't be surprised if they're coming down that channel at whoever's there.

"I'm confident going into games and I've just got to trust what I've done off the field is going to be enough to get me through on it.

"I've got no issues about defence."

More of a concern for Barnes is rebuilding an attacking combination with his erstwhile teammates after not playing a Test since last year's spring tour.

"Obviously I've got to learn all the plays again," he said.

"I've been out of the system here for a while. I'haven't been in the squad or training with them, but I don't think too much has changed from years gone by so I've just got to pick up those sort of things."

Barnes tried no end of "weird and wacky" remedies to treat his condition and said it was a big relief to be back playing in time to make his second World Cup squad.

"I worked pretty hard to obviously have a shot at this opportunity, so I'm pretty thankful that the selectors showed a bit of faith in me," he said.

"So I've got to repay it now I suppose."

Barnes will make his long-awaited representative return for the Australian Barbarians against Canada on the Gold Coast on Friday week and Wallabies coach Robbie Deans has no doubts his one-time former vice-captain is ready.

"You can see it in his eyes," Deans said.

"You can see it in the way he's playing the game and enjoying the game now."

Sydney University coach Todd Louden has been using Barnes at fullback and the 31-Test star said he was happy to be considered there for the Wallabies.

"To be honest, I've really enjoyed playing there," he said.

"I think that's something I'll be looking at in the future as well."

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