After winning the toss, Virat Kohli chose to bat first and scored a moderate 252 runs in their innings courtesy Virat Kohli's 92. Kohli missed his 31st century after an inside edge took his bells off.
But it was the outstanding bowling effort from Indian pacers who took away the match from Australia's hands.
Striker bowler Bhuvneshwar Kumar bowled his heart out to shatter Australia's top order. He conceded just 9 runs in 6.1 overs and claimed three important wickets.
Apart from Bhuvi, left-arm chinaman bowler Kuldeep Yadav rocked Australia and claimed his maiden hat-trick. When the hosts were looking well in the match, Yuzvendra Chahal's 34-2 in 10 overs broke Australia's backbone.
It was India's eighth successive win in ODIs and with victory in Kolkata, India have successfully dethroned South Africa from the no. 1 position in ODI team ranking to claim the top spot.
India: 252 all out in 50 overs (Virat Kohli 92, AjinkyaRahane 55; Nathan Coulter-Nile 3/51, Kane Richardson 3/55).
Australia: 202 all out in 43.1 overs (Marcus Stoinis 62not out, Steve Smith 59; Kuldeep Yadav 3/54, Bhuvneshwar Kumar3/9).