Sean Fitzpatrick, the former All Blacks captain, rates Brodie Retallick more important to New Zealand's bid to make it three successive World Cup title wins than Mako Vunipola's return from injury for England in Japan.
World Cup winner Fitzpatrick dismisses the suggestion a fit-again Mako Vunipola would be just as effective for England and puts Retallick in a class of his own because the rangy forward has a skill set no one else can replicate.
Lock is one of the areas the All Blacks could be found wanting if they suffer any more injuries with Retallick possibly missing all of the pool matches which start this Saturday with that titanic battle between New Zealand and South Africa, who have a wealth of second row power.
Retallick has not played since seriously damaging his shoulder against South Africa in Wellington on July 27 while Vunipola injured his hamstring in the August warm-up Test against Ireland having only just recovered from surgery after damaging the leg in the Heineken Cup final. Vunipola will miss England's pool games with Tonga on Sunday and USA, with a possible return pencilled in against Argentina on October 5.
Fitzpatrick told RugbyPass: "Retallick is crucial for the All Blacks at the World Cup and while they can still win without him, it would make it a lot better if he was there. You are going to need, as we saw in 2015, an entire squad effort if you are going to win the quarters, semis and final to lift the cup.