A fit Sonny Bill Williams would walk into the All Blacks World Cup squad - Steve Hansen

New Zealand coach Steve Hansen stated that Blues centre Sonny Bill Williams has only fitness to prove to be in contention for selection in the upcoming World Cup scheduled in Japan later this year.

Williams is among the 20 players in the history of the game to have won two World Cups that came in 2011 and 2015 and the upcoming edition in Japan will be his third successive showpiece event if he makes the cut.

The 33-year-old had a tough time with injuries last year that restricted his participation and suffered another setback in March when he injured his knee and followed it with a surgery.

Speaking about Williams' selection for the World Cup, Hansen said the former National Rugby League star has enough credentials to make it to the final squad provided he proves his fitness.

"I understand why people would say he's running out of time. But is he really?" Hansen told reporters in Auckland on Monday, adding that Williams was back running and would probably be available for the Blues again in two weeks.

"He's already proved himself. He's played 51 Tests. That's a lot of Test matches, that's a lot of proving.

"What we need to see is him getting back on the track. Then we've got to ask ourselves is his fitness good enough for him to be selected in the team?

"We play five Test matches before we have to name the World Cup team, so does he deserve the opportunity to show us whether he's still good enough?

"Of course he does because he's played 50 Test matches."

Meanwhile, Hansen also confirmed that Ben Smith, Owen Franks, Dane Coles and Brodie Retallick, who are all sidelined with injuries are making good progress.