A masterful 153 from captain Aaron Finch helped Australia to an 87-run win over Sri Lanka at the Cricket World Cup on Sunday morning (AEST).

Finch combined with Steve Smith (73) for a 173-run partnership – the highest of the tournament – as Australia posted a score of 7-334 at The Oval.

Sri Lanka threatened in response as openers Dimuth Karunaratne (97) and Kusal Perera (52) added 115 runs in less than 16 overs.

But Mitchell Starc (4-55) took a clutch of key wickets as the required run rate soared and Sri Lanka were bowled out for 247, Australia making it four wins from five World Cup matches.

Mitchell Starc took a number of key wickets to dent Sri Lanka’s run rate. Photo: Getty

Kane Richardson (3-47) also had joy with the ball but in truth, the scoreboard flattered Australia, who will need to finish better with the bat, and choose – and stick with – a frontline spinner if they are to win the tournament.

“It was nice to get a couple [of fours] away early and then get a few drives away, which is key to my batting … it’s a good sign,” Finch, who hit 15 fours and five sixes in his 132-ball knock, said afterwards.

“I thought we could have got 350 plus … [but] ‘Starcy’, as soon as he gets the sniff of a new batter, he’s all over him. He’s a world class bowler.”

Sri Lanka took 12 runs from the first over of its chase and that set the tone for a whirlwind hour.

Starc, Pat Cummins (2-38), Richardson and Jason Behrendorff (1-59) all came in for punishment and it took the introduction of Glenn Maxwell – at 0-87 after 10 overs – to stem the run rate.

A wasted review off Richardson’s bowling cost Maxwell a likely wicket when he trapped Karunaratne in front on 50, but Australia had no option to review the decision.

With the scoreboard precariously reading 0-112 off 15, Finch went back to his trump card and Starc duly delivered just three balls into his second spell, bowling Perera.

Only three boundaries came in the next 16 overs, a miserly stint that saw Lahiru Thirimanne (16) fall and led to Karunaratne’s dismissal, caught by Maxwell at backward point off Richardson.

Maxwell’s tidy bowling – he took 0-46 off 10 overs – was key in that period and after Angelo Mathews (9) departed, Starc dismissed Milinda Siriwardana (3), Thisara Perera (7) and Kusal Mendis (30) in just six deliveries, spread over three overs.

The triple-salvo assured Australia of victory and Richardson and Cummins mopped up the tail as Sri Lanka lost its last eight wickets for just 61 runs.

Earlier, Sri Lanka’s decision to bowl first looked like biting them as David Warner (26) hit the third ball of the match for four and Finch followed with a pair of glorious drives down the ground.

But Warner soon found the early going tough, a constant theme of his tournament, with Finch doing the bulk of the scoring.

Sri Lanka was desperate for an lbw review on Finch, then on 35, to go its way, but it was turned down on umpire’s call.

A wicket soon came, Warner bowled from the off spin of Dhananjaya de Silva, and the tweaker also dismissed Usman Khawaja for a scratchy 10.

David Warner and Aaron Finch celebrate after catching Thisara Perera of Sri Lanka. Photo: Getty

The run rate even dipped below 4.5 briefly before Finch clubbed three successive boundaries – two of them sixes – in the 29th over to reignite Australia’s innings.

And his hundred soon followed, brought up with a six, as Smith ran well and turned the strike over in what proved to be a very effective partnership.

Finch kept swinging hard, taking 31 deliveries to go from 100 to 150, but he and Smith were dismissed in successive overs, an untimely double blow that triggered a steady stream of wickets in the final few overs.

It left Maxwell to do much of the big hitting on his own as the Victorian hit 46 not out off 25 balls and pushed Australia towards 350 and, ultimately, a winning total.

But improvement is certainly possible for Finch’s Australia. You get the sense it will be required.