Australia leave India with the world number one ranking in one-day cricket and will return to the subcontinent for this year's World Cup with confidence after edging the hosts 2-1 in the series.

Australian white ball cricket looked to be at a crossroads only a few months ago, with Aaron Finch stepping down from the one-day captaincy and the Twenty20 team failing to reach the World Cup semi-finals on home soil.

Yet Australia's ability to quickly reset, rebound and ultimately dominate was on display again in India where they sealed the series with a 21-run win in Chennai on Wednesday under stand-in skipper Steve Smith. Read full story

It was India's first defeat in an ODI series on home soil since Australia beat them four years ago.

"I think in World Cup years, it can be very easy to look too far ahead," all-rounder Mitchell Marsh said. "But we really wanted to be focused on this series and make sure that our focus was winning games for Australia.

"So, really proud of the guys efforts to be able to beat the number one team in the world in their backyard.

"It's a great achievement ... Very proud of the lads and it's the first step towards our World Cup."

India host the 13th edition of the World Cup in October-November.

Australia, five-times champions in the 50-over World Cup, were missing bereaved regular captain Pat Cummins for the series and veteran opener David Warner for the first two matches but covered for them well.

Left-arm quick Mitchell Starc demolished India in the second match with a five-wicket haul while Man of the Series Marsh, opening the batting with Travis Head in place of Warner, topped the scoring with 194 runs at an average of 97.00.

While Adam Zampa was Man of the Match with a four-wicket haul, selectors will have been buoyed by the performance of Ashton Agar in Chennai where the second spinner turned the game on its head by removing Virat Kohli and Suryakumar Yadav in successive deliveries.

The left-armer had hitherto had a forgettable tour of India, being overlooked by selectors through the entire four-test series, which the hosts won 2-1.

"It's certainly been an indifferent, sort of, six-week period for him," said Marsh.

"But Ash is one of my closest mates and he's one of the most resilient characters that I know.

"And that's why he's been able to come in and perform whenever he plays for Australia."