There were times, when Finch, Smith and Maxwell were in full flight, and when Starc helped cut Sri Lanka down from 186 for 2 to their final tally of 247, when the Australians appeared irresistible; indeed, this win took them to the top of the competition table. But these moments were interspersed with issues that seem hard to fathom from a team contending for a World Cup, such as how Shaun Marsh ends up trying to start a top-order innings in the final five overs, and why Australia persist in ignoring Nathan Lyon as their best fourth-bowling option.
At some point in this tournament these issues will rear, as they did against India, also at The Oval, but Sri Lanka were neither confident nor accomplished enough to take advantage of the opportunities afforded them by Australian blind spots. They pulled Finch back from a rapid start but then allowed him to reset with Smith. They were able to sprint to 115 for 0 and then 186 for 2 before losing momentum and creating a scenario in which Starc bowled with scoreboard pressure behind him.
Even so, Finch's performance in particular was worthy of praise, being crisp and punishing in equal measure, and the contributions of Smith, Maxwell and Starc were very much in line with what the team expects of them. On current form, Australian look set fair to also defeat Bangladesh, meaning their final trio of games against England, New Zealand and South Africa will be met with a minimal degree of anxiety.
An overcast morning and a pitch tinged green swayed both sides to ignore their specialist spin bowlers and also Dimuth Karunaratne to send the Australians in - Finch would have done likewise. Immediately it was apparent that the surface was easier paced than expected with very little sideways movement, allowing Finch to get into stride with a series of beautifully crisp drives off both front and back foot - aided too by some substandard ground fielding.
David Warner, despite his Taunton century, was less fluent, rather mimicking his struggles at The Oval against India. The part-time spin of Dhananjaya de Silva put a clamp on the scoring and then found a way through Warner when he sought a way off strike by leaning back to try and cut off the stumps.
Usman Khawaja, returning to No. 3 after a couple of demotions, did not fare any better, having to swerve out of the way of a Nuwan Pradeep bouncer before trying to slog-sweep Dhananjaya and picking out deep midwicket. Sixty-nine for no loss after 13 overs devolved to 110 for 2 at the halfway point, but Finch and Smith needed only a brief few overs of settling down before going on the attack.
They were in many ways a perfect duo, Smith busy and inventive, Finch brutal and simple in approach. Between them they left the Sri Lankans with next to no margin for error, putting together a stand worth 173 from a mere 118 balls. Finch's hundred was his second in World Cups, and by the time he fell to an Isuru Udana slower ball, he had tallied the third-highest individual score by an Australian at the World Cup - putting Adam Gilchrist's 149 in the 2007 final in the shade.
Smith looked similarly intent on a hundred, only to be tunnelled under by a Lasith Malinga yorker that left the former captain looking to the heavens in frustration. But his innings had been a sparkling one, full of the energy and resolution that suggested he was fresh in both body and mind. Smith has not played a truly big innings in this tournament yet, but he looks ready to unleash one at a moment of import.
Maxwell's arrival brought a typical flurry, including 22 off Pradeep's final over to leave him nursing figures of 0 for 88 from 10 overs. At 302 for four with five overs remaining, a score in the region of 360 looked plausible, but Sri Lanka were to push back with the help of Australia's still-unbalanced batting. Shaun Marsh looked as suited to the middle order as Maxwell does the top order in cobbling three from nine balls, the resultant slowdown reaping a pair of run-outs as Malinga, Udana and Thisara Perera all finished well. Maxwell nudged a boundary from the final ball, but 32 from the last five overs might have been match-losing on another day.
As it was, Sri Lanka threatened for more than half the chase, starting out with a starburst of shots from Kusal Perera and Karunaratne that brought the many Sri Lankan supporters in the crowd to vocal life. Australia's liberal diet of short balls was feasted upon, and the curious decision to call up Jason Behrendorff and then not give him the new ball contributed to his first three overs costing 32.
When Kane Richardson made a speculative caught-behind appeal and Finch called for a review, the lack of any evidence on replay meant that when Maxwell pinned Karunaratne in front of the stumps from around the wicket, but far enough down the pitch for Richard Illingworth to say not out, there was no referral to discover that ball-tracker would have brought three reds and the first Sri Lankan wicket.
Finch, though, was able to bring Starc back, and a full, straight delivery knocked back Kusal Perera's middle stump. Karunaratne persisted, however, with help from Lahiru Thirimanne and Kusal Mendis, and at 186 for 2 in the 33rd over the game was well and truly alive. However, Karunaratne was slowed by the tidy bowling of Maxwell, playing the stopping role earlier performed by Dhananjaya, and in trying to cut his way from 97 to 101 found Maxwell lurking to take the catch in the gully.
Four wickets in four overs were soon to follow, three of them to the intimidating Starc - including two in as many balls removing Thisara and Kusal Mendis - the reward for pressure impose area but also the precision of the left-armer now well established in World Cup matches.
It was unsurprising in a few ways that things devolved so dramatically, for this is a Sri Lankan team short on confidence and experience, while the Australians are growing ever more confident of their ability to defend a target, not least when Starc and Cummins are lurking. Starc's haul took him to 13 wickets for the tournament - he is two clear of the next best, Cummins. In their fortunes, lie Australia's.