British and Irish Lions coach Warren Gatland believes Aaron Smith is the world's best player and the All Blacks will be a far less daunting prospect for next year's tourists without their scrumhalf.
Gatland, a former All Black, coached the Lions to a 2-1 series victory in 2013 in Australia and, on Wednesday, was handed the task of leading the international selection to a first series triumph in New Zealand since 1971.
Back in his native Hamilton on Saturday to watch the All Blacks beat Argentina 57-22, Gatland said Smith was a major factor in New Zealand's brilliant form this season.
"To be honest, I think they've taken the game on to another level," Gatland told New Zealand's Sky TV.
"I think there's one player in particular, in my opinion, who is the driving force and the key, and that is Aaron Smith. I just think he's the best player in the world at the moment.
"You take him out of that All Black team and they might be a little vulnerable - he's pretty special."
The Lions have won only one of their 11 series against the All Blacks and were swept 3-0 in the Tests in 2005 on their last visit, when England's World Cup-winning coach Clive Woodward was at the helm.
Gatland said he was hoping to watch all of New Zealand's remaining Tests in the Rugby Championship and the Third test against Australia in Auckland to follow.
The 52-year-old, who is handing control of the Wales squad to Rob Howley while on Lions duty, said he would name his backroom staff on December 7 and his squad in mid-April after spending some time with the England, Scotland and Ireland squads.
"It's a huge honour to be asked to lead the Lions again," he said. "I'm really looking forward to it; it's going to be a massive challenge but hugely exciting."
