The Women’s Twenty20 World Cup started off with a major upset as Indian leg-spinner Poonam Yadav derailed Australia in Sydney, with the hosts and reigning champions eventually bowled out 17 runs short with a ball to spare.

Yadav was denied a World Cup hat-trick by a dropped catch, and another wicket when the ball bounced twice on its way to the stumps, but she still finished with four wickets for 19 across her four overs, having completely trashed Australia’s chase.

Initially India’s total of 132 after being asked to bat looked well short, with a speedy outfield and lots of gaps making up for a pitch that was playing a little slow. That total looked even more comfortable just short of the halfway mark of the innings, when opener Alyssa Healy brought up her half-century from 35 balls, and Australia had 67 on the board for the loss of two.

Healy had been struggling for runs in the recent tri-series with England and India, but her irrepressible character meant she was never likely to let that worry her. She started her innings with 15 of the first 16 runs, going inside-out over cover as she always does in her pomp, and even with Beth Mooney and Meg Lanning giving up catches cheaply, it didn’t seem of great concern with Healy having dominated the scoring and the strike.

But Yadav’s introduction in the 10th over changed the game. Her fourth ball slipped from her hand to give Healy a comfortable full toss, with the Australian keeper cool enough to camp back and pull it over the midwicket rope. But the next ball dipped and landed perfectly, with Healy unable to handle the loop so that she chipped back a return catch.

From there, Yadav was in her stride. She cuts a singular figure on the field: barely a metre and a half tall, seeming impossibly tiny from the grandstand, and evoking thoughts of a more amateur style when she loops up her slow, high leg-breaks. But she has been very much a fixture of India’s shift to a successful modern team, with her skill in variations, turn, and landing the ball making her a deceptively difficult prospect.

In her second over Yadav unleashed a string of wrong’uns that ran through Australia. The delivery turned away from the left-handed Rachael Haynes, who was stranded trying to reach the pitch of the ball and was comfortably stumped by Taniya Bhatia. Ellyse Perry has the best defence in the world, but the right-hander also walked at Yadav and was bowled first ball as the googly turned back through the gate and took leg stump. Then came Jess Jonassen, another lefty, whose thick edge from a push went fractionally too high and wide for Bhatia to comfortably get the gloves to it. A hat-trick was deflected into the dirt.

But the Australians were rattled, and both Yadav and Bhatia shook off the disappointment, teaming up again in Yadav’s third over to remove Jonassen via an edge from a sweep at another googly that turned across the batter. Yadav’s time in the air had everyone’s timing in a mess.

Australia still had Ash Gardner and Annabel Sutherland, two of their sweetest strikers of the ball, with 51 runs needed from six overs. With Gardner hitting and clearing the boundary over the next couple of overs, a recovery still looked on. But Bhatia ended that with a brilliant stumping from seamer Shikha Pandey, collecting the ball out wide near the return crease and diving into the stumps.

Yadav returned to bowl Gardner with a drag-down that kept very low, but replays showed it had bounced twice before reaching the crease. Under recent law changes that was now a no-ball. But Gardner couldn’t score from the free hit, and Yadav finished the over without the wicket, but having conceded only three singles and the extra. With 27 needed from two overs and three wickets in hand, frantic hitting and running saw Australia fall away.

With the bat, India had Deepti Sharma to thank for what ended up being a defendable total, as she calmly assembled an unbeaten 49 after a fast start soon became 47 for 3. This Indian batting side looks most comfortable in the chase, with a set target ahead of them, but batting first can look lost for a plan.

Shafali Verma and Smriti Mandhana were going at 10 an over through the first four, but Mandhana aimed a huge sweep shot at Jonassen’s first ball of the day without even a look, and missed to be plumb leg before for 10. So often her captain Lanning’s go-to when situations are getting out of hand, Jonassen pulled the scoring back beautifully. Verma holed out against Perry after a fast 29 from 15 balls, then Jonassen had India’s key Harmanpreet Kaur stumped for two.

With India’s batting frailties starting at number seven, Deepti and Jemimah Rodrigues (26 from 33) had to play a sensible accumulation game and hope that a modest total would be enough. As it turned out, thanks to first-night nerves and one brilliant bowling performance, it was. India take first points in Pool A, with Bangladesh, New Zealand and Sri Lanka to come.