All Blacks wing Julian Savea has been suitably humbled and that's bad news for the Wallabies.

For the opening three tests of World Cup year New Zealand's most potent strike weapon has been a notable absentee from the teamsheet. The full reasons for that have emerged in Sydney this week with coach Steve Hansen saying his star wing had turned up to the All Blacks first training camp overweight and out of shape.

However, in Sydney on Thursday Savea put his hand up for letting his conditioning slip during the Hurricanes' Super Rugby campaign.

"It's always hard when you are playing week in week out. Your eating stays the same or even increases, but the training load comes down," he said. "You don't get that conditioning every week. The All Blacks coaches made a decision [not to play me until I was fit] and I agreed with them and responded really well and basically worked my ass off."

That meant some humbling fitness sessions with trainer Nick Gill, one in Johannesburg ending with Savea down on all fours and reaching for his asthma inhaler.

"Pretty much just running. Running up and down the field while the boys are training," Savea said of his fitness schedule. "It's been pretty good, it's worked really well. In terms of my goals I just wanted to get in good shape and be ready to go when I got the opportunity… the last couple of weeks has been really rewarding to see the changes and I'm happy with where I'm at. It doesn't stop there I just have to keep working hard."

Savea said the asthma related incident in South Africa was not an issue of any ongoing concern.

"It was nothing out of the ordinary. It always happens. There's nothing strange about it. Everyone who knows me, in my family, knows it happens. I could have one sitting down right now. It's all under control."

That said, Savea will know his slip in standards was not a good look in World Cup year, particularly as it came shortly after he and lock Brodie Retallick had signed highly publicised four year deals with New Zealand Rugby.

Coach Steve Hansen was clearly not overly impressed to discover one of the gems in the All Blacks crown was out of shape, but said Savea had been quick to take responsibility and go about putting things right.

"We're trying to get him fit. He turned up overweight. His attitude to that task has been fantastic and he's done what he's been asked to do. He's made some great gains and been through a bit of pain.

"He's pretty hungry, and I don't mean for food, I mean for a game. And that's a good place to have him because when he's like that he's a pretty handy footballer.

"It's a big season and sometimes those things can creep up on you. He's a first time dad as well, so he's dealing with different things at home and over a long season of Super Rugby you can lose focus, so maybe that happened a little bit... he's accepted he wasn't where he needed to be. He's worked hard and now he's ready to play."

For Savea, the chance to get his test career back on track in Sydney cannot come any faster.

"You always want to pull on that black jersey and be out there with the boys, but I knew that wasn't my role at the moment. My role was to get right and help the boys prepare for every test.

"But if there was a scale one to 100, I'm a 100. I just want to get out there and put in a good performance for the team."