All Blacks: The hunt is on - who will replace Damian McKenzie in World Cup squad?

Damian McKenzie's ruptured knee ligament, which will keep him out of all rugby for the rest of the year, will force the All Blacks selectors to up their search for the country's next-best first-five, an individual who is not immediately obvious.

They will want to take another specialist No10 to the World Cup in Japan which starts in September to cover for Beauden Barrett and Richie Mo'unga, and the beauty of McKenzie was his impact value from the bench and his ability to cover fullback as well.

It goes without saying that his extended period on the sidelines following the ACL injury which he sustained while trying to tackle Blues first-five Otere Black during the Chiefs' 33-29 thriller in Hamilton on Saturday will also hinder a franchise which has re-found its mojo over the past three weeks.

Brett Cameron, Mo'unga's back-up at the Crusaders and a replacement in the test against Japan last year, is the only other capped first-five specialist currently playing in New Zealand and his form this season, particularly when starting in his team's defeat to the Waratahs in Sydney, suggests he has plenty of developing to do yet.

Other possibilities are the Blues' Black, a 23-year-old New Zealand Maori player and former under-20s representative, and Josh Ioane and Bryn Gatland, also both 23, at the Highlanders.

Stephen Perofeta, 22, has yet to play a competitive match for the Blues this year after suffering a pre-season chest injury, a latest problem in a fairly long list. Had he been fit at the end of last year he probably would have gone to Japan instead of Cameron, while Blues' teammate Harry Plummer, 20, has promise but isn't ready.

Of them all, it is perhaps Black who strikes as the best bet for his composure and consistency over the past couple of weeks when starting for the Blues. His recent rise ahead of Plummer, with whom he swapped the No10 jersey initially, has clearly given him confidence and he is thriving on the responsibility and game time.

The selectors could be forgiven for casting a rueful glance at 28-year-old Hayden Parker, the former Highlanders first-five now doing incredible things for the Sunwolves with not only his goalkicking, which is nearly flawless this season, but his general play for the perennial battlers. Under New Zealand Rugby's regulations, Parker isn't eligible for the All Blacks as he isn't playing for a Kiwi franchise.

For McKenzie, who didn't attend the All Blacks' foundation day in Wellington today, the news will be devastating and it has a strange echo to four years ago when Chiefs No10 Aaron Cruden suffered the same injury in Christchurch almost to the day.

"He's done an ACL so it looks like he might be out for eight to nine months which is a real shame for him," said All Blacks coach Steve Hansen today in announcing McKenzie's diagnosis. "His Word Cup opportunity is gone.

"He's still young enough to probably make the next two so it's just important that he gets his knee right and takes the time to come back so he can achieve the dreams he wants to achieve. It's sad for him obviously it creates an opportunity for somebody else. We've got to accept injuries and there will be more than just him [before the World Cup] I'd suggest."

Cruden's injury on April 17 before the All Blacks 2015 World Cup defence was a huge blow for himself, the Chiefs and the national team, but Hansen had three very clear options for his playmaker in the form of Daniel Carter, Beauden Barrett and Colin Slade.

Lima Sopoaga also went very close to making the trip to England and Wales after leading the Highlanders to their first Super Rugby title and impressing in his test debut in Johannesburg.

Four years later, however, Hansen's options are not so obvious and an injury to either Barrett or Mo'unga, or heaven forbid both, would be potentially catastrophic to the team's chances of making history again, this time by winning three in a row.