Dhoni, the world's highest-paid player, produced his best performance of the six-week-long event when it mattered most as India passed Sri Lanka's total of 274-6 with 10 balls of the allotted 50 overs to spare.
The 29-year-old smashed the winning runs with a huge six over the boundary ropes to finish the innings unbeaten on 91 off only 79 balls faced.
He set up victory with his fourth-wicket partnership of 109 with Gautam Gambhir, who top-scored with an invaluable 97, after coming to the batting crease at 114-3 in the 22nd over.
Sri Lanka, winners of the tournament in 1996 and runners-up in the last staging four years ago, set a potentially testing target for India thanks to an unbeaten 103 from captain Mahela Jayawardene.
With the victory, India — the top-ranked team in cricket's five-day Test format — assumed the No. 1 position in the limited-overs game ahead of previous champions Australia.
More here. [Photo shows Sachin Tendulkar.]