New Zealand won the toss and elected to bat in their maiden World Cup final on Sunday, looking to cap an unbeaten streak by defeating co-hosts Australia at the Melbourne Cricket Ground.

Some 90,000 fans at the vast stadium and millions of television viewers around the world will follow the blockbuster title clash between the two best teams left standing in the 14-nation, six-week event.

Brendon McCullum's Black Caps have won eight matches in a row, including a one-wicket victory over Australia in a low scoring pool stage thriller in Auckland a month ago.

Then at the same Eden Park last Tuesday, New Zealand downed mighty South Africa in a nerve-tingling semi-final with a penultimate-ball six by Grant Elliott.

Both sides fielded teams from their semi-final wins, with Australia sticking with the same side that beat world champions India in Sydney.

New Zealand's first semi-final win in seven attempts has left an enthralled rugby-mad nation backing their cricketers to take home the sport's biggest prize.

"I want you to know it's this sense of belonging that we take into the final today. What's our motivation? Our motivation is to play for you," McCullum wrote in an open letter published by the New Zealand Herald on Sunday.

"Make no mistake, we've felt your belief. We've heard the chants, the cheers and the roars. We've seen the emotion in the faces of the children; in the faces of the mums and dads, and the grandfathers and grandmothers.

"We've seen grown men in tears; we've seen strangers hugging and we've seen the elderly dancing. I'm not sure how to say this but we've never felt quite so 'New Zealand' in all our lives."

Australia, the top-ranked side in one-day cricket bidding for a fifth title, will be considered favourites on home turf at the MCG where New Zealand last played a one-dayer in 2009.

But even as the confident Black Caps named an unchanged side for the decider, Australia were taken aback by skipper Michael Clarke's announcement on Saturday that the final will be his last one-day international match.

"I think it's the right time for me and the Australian cricket team," said the 33-year-old Clarke, who will, however, continue to play five-day Test matches.(AFP)