A dazzling half-century from Marcus Stoinis was enough to drag a still-rusty Australia to a crucial victory over Sri Lanka in Perth, to get their T20 World Cup defence back on track.

Stoinis bludgeoned six sixes in an unbeaten 59 off just 18 balls, the fastest-ever 50 from an Australian in a T20I, to steer the reigning champions to victory by seven wickets with 21 balls to spare, providing a crucial net run rate boost after their disastrous loss to New Zealand in the tournament opener.

But the hosts still have a series of questions that urgently need answering heading into another must-win game against archrivals England on Friday night – chief among them the form of captain Aaron Finch reaching a painful new low.

Struggling to hit the ball off the square for much of the innings, Finch laboured through a painful 42-ball 31 made all the more humiliating by the dominance of first Glenn Maxwell (23 off 12) and then Stoinis at the other end.

With Cameron Green waiting in the wings having shown exciting signs at the top of the order in the lead-up to the tournament, and space needing to be found for Ashton Agar as well after a miserly bowling spell as a last-minute replacement for the COVID-stricken Adam Zampa, Finch’s captaincy is the last thing keeping him in the Australian XI.

And it’s unclear just how long that status can continue to save him.

This can't go on

— Daniel Cherny (@DanielCherny) October 25, 2022

“My innings was unusual, it was poor – I just couldn’t hit the ball,” a candid Finch admitted after the match.

“They bowled a hard length, it was tough – it’s such a big ground that you feel as though it’s hard to stand and deliver. Especially with a bit of extra bounce, and when the ball’s seaming slightly, you feel it’s just not quite as easy to hit the middle of the bat.

“That’s no excuse for the way I played, but it was nice to get the two points.”

While Zampa was the only change to Australia’s line-up after failing to recover in time for the match, Finch was quick to prove the hosts weren’t averse to improvising on the fly following their disastrous loss to New Zealand in Sydney.

Mitchell Starc was stripped of the new ball after being taken apart by Finn Allen on Saturday night, with Josh Hazlewood and Pat Cummins instantly proving the change was a wise one.

Hazlewood regularly beat the bat of Sri Lankan opener Pathum Nissanka in a typically incisive opening over, while Cummins would go one better by removing the in-form Kusal Mendis for just 5, failing to get over a short ball and ballooning a simple catch to Mitchell Marsh at mid-wicket.

Things wouldn’t remain that easy for long, though; Nissanka and Dhananjaya de Silva first consolidated, then targeted the Australians’ weakness: their reserve bowling.

Moving cautiously to 1/63 after 10 overs, the first sign of upping the ante came when de Silva aimed to loft Marcus Stoinis over his head, with David Warner doing magnificently to prevent a six millimetres from the boundary: running back with the flight to long off, taking the ball and tossing it back into play just as his momentum carried him over the rope.

Warner would go one better an over later, completing a de Silva catch as the Sri Lankan again tried to bully Ashton Agar down the ground: so easy did he make the catch look that one could almost be tricked into underplaying the extreme degree of difficulty.

The problem was the dismissal brought Charith Asalanka to the crease, who immediately showed just why he’s regarded as one of the men set to carry the next generation of Sri Lankan cricketers back into prominence on the world stage.

A monstrous lofted drive off Mitchell Marsh from just his fifth ball, comfortably reaching the Optus Stadium stands, was without question the shot of the evening… and added insult to injury for Cummins, who had shelled a straightforward chance to remove Nissanka just one ball prior.

It was the latest and costliest in a string of fielding mishaps from the Aussies, and tensions were beginning to show as the reigning champions’ title defence remained on the brink. A throw from third man from Starc that reached Wade on the half-volley brought with it a foul-mouthed tirade from the passionate wicketkeeper.

Through it all, Agar, an eleventh-hour selection following the withdrawal of Zampa, couldn’t have done more to prove his worthiness for the remainder of the tournament – even if it needs come at the expense of one of the three premier quicks.

Like most left-arm slow bowlers, Agar’s turn is negligible, but his crafty changes of pace and length proved tremendously difficult for the Sri Lankans to handle, just as it had against the same opposition in February this year when he famously conceded only singles across 12 overs in the three-match series.

It was his accuracy that brought about the downfall of Nissanka – attempting to bring the freewheeling Asalanka on strike, the opener attempted to manufacture a nonexistent single after tapping straight to Marsh at point, only realising his mistake when stranded halfway up the pitch.

Agar would finish with a superb 1/25 from his four overs, the one blemish a four down the ground in his first over from de Silva. Given what he brings to the team in the field and as a handy middle-lower order batter, the question now must be who else will make way for the returning Zampa against England on Friday night.

It could be Cummins, who, with Hazlewood (1/26) miserly as ever and Starc (1/23) adjusting well to a new middle-overs role, leaked badly in the final over of the innings as Sri Lanka, after appearing resigned to a total on the cusp of 150, suddenly found themselves with 157 to defend.

Taken apart by Asalanka, in particular with a stunning lofted drive into the stands, Cummins lost his range and repeatedly failed to hit his yorkers – though admittedly, a final-ball boundary from Chamika Karunaratne was scarcely his fault.

A low full toss was dug out into the covers, where Finch, looking every inch his 35 years as he ambled towards the ball, made a hash of a straightforward stop. It would prove a sorry portent of things to come with the bat.

While the Sri Lankan spin trio of Wanindu Hasaranga, de Silva and Maheesh Theekshana seemed the main threat for the Australians heading in, it was in fact pace that once again left Finch all at sea early.

Despite the visitors’ pace bowling stocks taking another hit with Binura Fernando limping off after just five balls in the opening over, Karunaratne and Lahiru Kumara would step up to give the captain and Warner a serious working over.

Finch would play and miss repeatedly in an incisive over from the latter ruined by a wayward ball down the leg side that beat Mendis for five wides; with Karunaratne peppering Finch from back of a length or targeting the vulnerable front pad, there was no respite.

Extras were the only salvation, with a searing inswinger from Kumara cutting Finch in half, and too good for Mendis to stop, racing away for four byes.

“Happy to take any ideas if you know how to hit that,” Finch joked with umpire Richard Illingworth; what wasn’t laughing matter was that, for the first time in Australia’s T20I history, not a single boundary had been struck off the bat in the PowerPlay.

With Warner falling for 11 trying to assert himself on Theekshana’s first ball, drilling the spinner straight to captain Dasun Shanaka at slip, the Sri Lankans were well on top.

As it was repeatedly in last year’s World Cup, it was Marsh who turned things around. Committed to targeting the spinners after seeing off the quicks, the usually menacing Hasaranga was swiftly neutralised by the powerful Western Australian, using the reliable bounce to hit crisply through the line.

Between a powerful pull shot past deep mid-wicket – the Aussies’ first boundary off the bat from the 44th ball of the innings – and a salivating crunch over Hasaranga’s head, Marsh and Finch clubbed 15 from the over to instantly turn the worm the right way.

Even Finch at last got going, breaking the rot with a mighty heave over cow corner to start de Silva’s next over; and while Marsh would try one big shot too many and find Bhanuka Rajapaksa at long off for 16, he had done enough to turn the momentum.

Glenn Maxwell, already riding high after winkling out Shanaka with the ball, followed suit. Perhaps the only Australian to take the fight to New Zealand with the bat at the SCG, the Victorian dynamo confirmed his horror run of form heading into the World Cup has well and truly subsided.

Continuing the onslaught against the Sri Lankan spinners, this was a more conventional assault than the myriad of switch-hits he’d brought out against the Black Caps, clubbing Hasaranga against the spin for two sixes in the over to race to 22 off just six balls.

Hasaranga, normally Sri Lanka’s strike bowler, had conceded 34 from his two overs, and effectively been hit out of the attack.

Things, though, shifted again when Shanaka returned to his pacemen. Kumara took no time at all to return serve on Maxwell, first rapping him on the gloves, then following up with a short ball that honed in on Maxwell’s neck past his swipe across the line.

Felled, the Australian needed several minutes to recover, and it would prove the end of the carnage; an over later, he attempted to launch Karunaratne over deep mid-wicket, with sub fielder Ashen Bandara clinging to the catch just millimetres from the rope.

Amidst the drama, Finch again found himself becalmed: playing out six dots from Theekshana to halt the momentum, only a bizarre triple-bobble of a difficult catch running back with the flight from Bandara the ball before Maxwell’s fall keeping him in the middle.

Such was the disparity of form between the pair that praise of Bandara’s quick-thinking to drop the struggling Finch and claim Maxwell was only half in jest.

Bandara dropping Finch then catching Maxwell the next ball in a moment of extreme game awareness.

— Daniel Cherny (@DanielCherny) October 25, 2022

It fell to Stoinis to revitalise the run rate; while not as fluent as Maxwell, his flurry was even more prolific.

Beginning with a streaky uppercut down to third man off Karunaratne, then following with a bottom edge to fine leg and another outside edge through the vacant slip cordon, Stoinis had reached 15 off six balls having hardly middled a single one.

But he’d make up for it by joining Maxwell in taking Hasaranga apart again; with the spinner utterly rattled by the onslaught, his length would drop short time and again, allowing the powerful Stoinis to deposit him twice over long on in between a sizzling four back over the bowler’s head.

Remarkably, Hasaranga had conceded 50 runs by his 17th ball – the first time in his previously exceptional T20I career he’d been hit for that many.

There's only one Player of the Match #T20WorldCup pic.twitter.com/1FKayUeNqZ

— cricket.com.au (@cricketcomau) October 25, 2022

“It was a pretty special innings,” Finch said of Stoinis’ surge.

“To come out with that intent, I think is the main thing. When you walk out to bat and you have that presence in the crease, that’s half the battle in T20 cricket.

“When you’ve got the skill and the strength that he’s got, it’s a pretty good combo.”

Stoinis proved an equal opportunity destroyer in the next over by blasting Theekshana for repeated sixes as well; while the run rate dwindled in rapid time as the Western Australian reached an Australian record 17-ball half century, it wasn’t exactly relieving the pressure on Finch.

As with Maxwell, the disparity between the pair’s striking was utterly absurd; while Stoinis was clearing the pickets with the greatest of ease, it was all the captain could do to lay bat on ball.

Eventually they won, and the power of Stoinis is a plus, but Australia were scrappy and still don't have the look of a champion. And Finch must be feeling miserable.

— Harsha Bhogle (@bhogleharsha) October 25, 2022

One particular ugly heave off Theekshana trickled off the inside edge down to long on for one, bringing with it a disbelieving cry of ‘Oh my God!’ from Finch. It could just as well have been on the lips of everyone watching on, too.

Somewhat ironically, Finch finally found the middle for the winning runs, clipping Kumara over mid-off for two to secure victory in the 17th over – though with Bronx cheers echoing around Optus Stadium, it couldn’t disguise his almighty battle in the middle.

Jokingly bowing down to Stoinis, Finch showed an endearingly good humour about his performance; but with so many alternative options, Green chief among them, clamouring for a chance at the top of the Australian order, change appears imminent and necessary.

Aaron Finch bowed down to Marcus Stoinis after the match. pic.twitter.com/VQKfVGurnZ

— Mufaddal Vohra (@mufaddal_vohra) October 25, 2022

The result sees Australia’s net run rate improve to -1.555 – still well and truly off the pace in Group A. But for Finch and company, a win to restore confidence was priority number one.

And for everyone, except the captain, that’s just what was achieved.