Returning Wallaby Matt Giteau has revealed that he feels his call-up is unjustified because he has not played against his team-mates this year.
Giteau joined wing Drew Mitchell is being named in Australia's training squad for the Rugby Championship, with the overseas law relaxed to allow the move.
But the Toulon star says it has been tough to feel like he's earned his spot.
"It feels like it is unjustified that we've been picked, that's how I feel," Giteau told Australia's Daily Telegraph ahead of their home game against South Africa.
"The rules have just come in. It is very fresh… we have been playing in a different competition, we haven't been playing against those guys in the Australian derbies, so we haven't really had a chance to measure yourself up against them. You haven't outplayed them, in some ways.
"So that's where you feel the justification may not actually be there."
He added: "It is like when I first came into the Wallabies, you have to find your feet and find within yourself that you belong.
"That it is a level you can handle, and that you can add to the group. Every training session I am out there trying to prove myself and earn the respect of the players and the coaching staff.
"A World Cup is a huge honour and a huge occasion. It is not something I want to take lightly, or disrespect the jersey by playing if I am not up to it."
Giteau however feels he has matured and grown as a player since he departed Australia's shores to join the Top 14 and European heavyweight side.
"Certainly (compared to) when I left, yeah," he said.
"I have got to play in some big finals and we have won some comps. In those tight situations, those big games, you learn more and you become more relaxed. The more relaxed you are the better you are going to play, the more natural your game will be."