All Blacks coach Steve Hansen is understood to be leaning towards the shock inclusion of Highlanders wing sensation Waisake Naholo in his World Cup squad of 31 to be announced on Sunday.

Naholo suffered a fine fracture to his fibula during a promising test debut for the All Blacks against Argentina in Christchurch in July.

At the time the injury was given a three-month recovery timetable and Naholo was presumed to be unavailable for selection for the World Cup squad.

But the situation has changed dramatically in recent weeks with the 24-year-old, who scored a record-breaking 13 tries for the Highlanders in 2015, said to have made significant progress on the back of "alternative" treatment undertaken in his homeland of Fiji.

Hansen admitted after the All Blacks dispersed following their Bledisloe-clinching victory over the Wallabies in Sydney that Naholo was now a "possibility" to make the World Cup squad.

"We know where he's at. We've seen him since he's been over in Fiji, and all we can do is get some X-rays, see how it's going and follow the medical procedures," Hansen said then.

"He's likely to be ready to play if we wanted to take him round about the third game. That's another consideration we have to take into account - do we want to take that risk and take him or do we leave him at home?"

It's understood latest scans on Naholo reveal the fine fracture in his leg has healed. That might convince the All Blacks to roll the dice and take their potential game-breaker to England.

The All Blacks refused to reveal details of Naholo's latest tests when contacted on Monday and said that information would not be made available until Sunday's squad announcement.

The timetable for his return would remain at the third game but it appears to be a risk that Hansen is now considering as squad selection cutoff looms.

Whether Naholo would be taken as an extra back-three player, at the expense of possibly a third halfback, remains to be seen. Ben Smith and Julian Savea are the selection certainties in the fullback/wing mix, while Nehe Milner-Skudder appears to have booked his spot after back-to-back standout tests against Australia and a strong nod of approval from Hansen.

That leaves Charles Piutau, a fit-again Cory Jane and Israel Dagg vying for probably one more spot, though Naholo's inclusion would have to come either at their expense or a player in another position.

The Fijian-born flyer is rated highly by Hansen after his sizzling season for the Highlanders. New Zealand Rugby encouraged and supported him in his decision to back out of a contract with Clermont in France to recommit to the Kiwi game.

Hansen's key decision now is to decide whether he goes with just Aaron Smith and TJ Perenara to cover halfback for the tournament, with Colin Slade as a potential makeshift fill-in.

Tawera Kerr-Barlow is the likely third halfback if one was taken. It is understood Canterbury veteran Andy Ellis now sits outside the RWC mix.

First five-eighth is the other main area of selection interest with Slade's versatility likely to give him the edge over Lima Sopoaga who impressed so much in Johannesburg.