Aaron Finch's tournament-equaling high score of 153 led Australia to an emphatic 87-run victory over Sri Lanka at The Oval which saw them move to the top of the World Cup table.
Finch's 132-ball innings included 15 fours and five sixes as Sri Lanka were set a daunting 335 for victory but Dimuth Karunaratne's side looked on course for a shock win as the captain and Kusal Perera (52) put on 115 for the first wicket.
But, Karunaratne was caught off Kane Richardson three runs short of his maiden one-day international century as Sri Lanka collapsed from 186-3 to 247 all out.
Australia's fourth victory in this summer's campaign moved them to the summit of the 10-team table for the first time while their opponents remain fifth, having picked up a sole win from their five matches.
Finch's apparent misfortune of losing a fifth successive toss proved to be a fruitful near miss, with the Australian skipper having said at the start of the day that he too would have opted to bowl first had he had the chance.
After being put in to bat, the 32-year-old began in his usual free-flowing manner and although a continuing out-of-sorts David Warner was bowled by Dhananjaya de Silva for 26 to end an opening partnership on 80, Finch continued to bat with freedom.
De Silva nabbed Usman Khawaja six overs later but it brought Smith and the batsman's presence allowed Finch to unleash, racing to his hundred off just 97 - the latter half-century including four maximums.
With boundaries flowing and a score of 350+ looking a minimum, Finch whipped Lasith Malinga over square leg for four to move to 150 but fell in the next over when he skied Isuru Udana to cover.
It triggered a frenetic ending to Australia's innings: Malinga bowled Smith (73) with a classic yorker, Maxwell smashed Nuwan Pradeep for 22 from the 45th over before Udana then ran out Alex Carey (3) and Pat Cummins (0) in the same over.
Having managed to restrict the Baggy Greens to 334-7, Karunaratne and Kusal Perera started Sri Lanka's chase in spectacular fashion, pummeling 87 from the first 10 overs - the highest score in the opening powerplay of the tournament so far.
Such was Australia's frustration with the burgeoning stand, Finch called for review in the 10th over for a possible Perera caught behind chance off Richardson but replays showed the no edge.
Just 16 balls later, Glenn Maxwell's shout for an lbw against Karunaratne was turned down but Australia were unable to call for a review - which would have seen them earn the wicket they were so desperate for.
However, Perera was bowled by Mitchell Starc (4-55) to break the first-wicket partnership and all but end Sri Lanka's momentum - they scored only a further 11 boundaries in the rest of their entire innings.
Karunaratne ultimately lost his wicket as he looked to launch a short and wide delivery from Richardson away to boundary but succeeded only in picking out Maxwell at backward point.
The wickets then tumbled as Sri Lanka lost 8-61 to be bowled out for 247 in 45.5 overs and end an entertaining contest at The Oval.