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Will Genia says the Wallabies will be inspired by the return of veteran flanker George Smith for Saturday's series-deciding showdown with the British and Irish Lions in Sydney.

The influential scrum-half on Friday described the 32-year-old open-side flanker as a "freak" with an aura that will lift the Australians at the Olympic stadium, in their biggest match since the 2003 World Cup final against England.

Coach Robbie Deans opted for the experience of the 110-Test veteran in selecting Smith over Michael Hooper in his only change to the Wallabies' side that levelled the series with a gritty 16-15 win over the Lions in Melbourne last weekend.

Smith, the sole survivor of Australia's series win over the Lions 12 years ago, has recovered faster-than expected from a hamstring injury but has not played a match for six weeks.

Genia, who has been one of the Wallabies' standout performers in this fiercely-fought series, said Smith's presence had lifted the team going into the crunch Test.

"George is a freak. He's come back earlier than expected (from injury) and he looks in great shape. He's running around like he's 21," Genia told a press conference on the eve of the match.

"He's got great enthusiasm, he's got great respect from the guys and great respect from people in the game. He offers so much with his experience, with his ability at the breakdown.

"For a lot of us, he has an aura about him and to have him in your side means a lot and definitely gives me a lift coming into this Test."

Hooker Stephen Moore, a teammate of Smith's at the ACT Brumbies, credited him with evolving his style of play over his career, comparing him to All Blacks skipper and number seven Richie McCaw.

"If you look at those great players, and Richie McCaw is a great example, they've adapted their games throughout their careers, they've added new dimensions to their games," Moore said.

"George is a different player than he was when he last played against the Lions 12 years ago. He's really matured and physically he's always kept himself in great shape and he's a freak in that respect.

"I've never seen him tire in a Test match no matter how much rugby he's played."

Genia said he was confident the Wallabies' best rugby was ahead of them going into the series decider against the Lions.

"We can honestly say we haven't played our best footy throughout the series thus far and probably we've made too many errors to give ourselves an opportunity to play any sort of fast flowing rugby," he said.

"We were able to do that in the last 20-30 minutes in the second Test in Melbourne and the thing is we will take a lot of confidence out of that moving forward.

"I think we have been chasing the game a little bit too much in the last two Tests and playing off the back foot.

"So if we can start well and give ourselves a good opportunity to get into the game then we definitely back ourselves to play some good rugby and really have a go."