Sonny Bill Williams believes he has the fitness and improved maturity to play a pivotal role in New Zealand’s hunt for a fourth Rugby World Cup triumph.

The star midfielder will be the oldest member of the All Blacks squad in Japan at 34 and is in line to claim an unprecedented hat-trick of winner’s medals, alongside captain Kieran Read and Sam Whitelock.

Williams’ impact should be greater than in 2011 and 2015.

He played in all 14 matches across the two tournaments but started in just five. Only one of the starts was a knockout game – when he filled in on the wing in a quarter-final against Argentina eight years ago.

But the former NRL star is rated so highly by coach Steve Hansen that he can expect to start all of the looming big Tests at inside centre.

Williams agrees he has matured from the code hopper who boasted attacking x-factor in spades when he took his career from France to Christchurch in 2010.

Packing rugby’s best offload wasn’t enough to win regular selection over retired greats Conrad Smith and Ma’a Nonu.

“In my younger days it may have been about getting on the highlight reels and making big plays but now I know to be a good team player you don’t have to do that fancy stuff,” Williams told Radio Sport on Sunday.

“Although, when I’m on song that stuff comes naturally. If I can open up space elsewhere by attracting players then I’m doing my job.”

Williams is still to announce his post-World Cup plans but admits a three-year battle with injuries has tested his patience.

Knee surgery and other niggles ruined most of 2019 and a Japan ticket was only confirmed through a compelling display in last month’s 36-0 Bledisloe Cup decider rout of the Wallabies at Eden Park, where he scored his 12th try in 53 Tests.

“Against Australia and in those big games; I thrive on those moments because they are the biggest stages where you can create history.

“I love those types of moments.”

Even then, Williams was unsure he’d done enough, admitting to anxiously watching a live All Blacks squad naming for the first time.

The tears from his wife and brother upon hearing his name read out brought home the magnitude of his battle with injuries.

“To be honest, it has been really tough and I’ve had to show a lot of resilience,” he said.

“A skilled sailor was never made in smooth waters and I’ve definitely struggled in that respect over the past few years.”