Ashleigh Gardner has revealed she was still feeling the effects of her recovery from Covid during a stunning all-round performance that helped propel unbeaten Australia to the top of the Women's World Cup table with a commanding victory over New Zealand.

Gardner built on the foundation set by Player of the Match Ellyse Perry and Tahlia McGrath after an extremely unsteady start to smash 48 not out off just 18 balls as Australia reached 269 for 8 from 56 for 3. Gardner then took 2 for 15 from 3.2 overs as New Zealand were bowled out 141 runs short with nearly 20 overs to spare.

All that upon making her return from Covid, which had kept her out of Australia's first two victories and in isolation for 10 days, with relatively mild symptoms.

"I was pretty lucky, really," Gardner said. "My first symptom was just having a sore throat... and then I just had a consistent headache, probably for about a week. From a week onwards to the end of the isolation period, I fell back to normal.

"Obviously, today was always going to be a test with how I was going to feel. Early on, I was getting a little bit puffed running on the boundary, but the main thing out of the game was, I just felt like I had a really heavy chest at points, which is quite a weird feeling. But other than that, I'm feeling pretty good."

Absent from Australia's 12-run win over England and seven-wicket defeat of Pakistan, Gardner admitted she was unhappy with her form in the nets on the eve of the match and it took some words of encouragement from Matthew Mott, Australia's head coach, to put her in the right frame of mind.

"I guess there's a lot of confidence involved," she said. "[In] my first training session yesterday, I hit the ball pretty badly and I was pretty frustrated with that preparation going into today. Motty was just telling me, 'just take the confidence out of what you were doing before you went into that isolation period'. I just tried to do that.

"I think the platform that the girls set for me to go out there with was really good. I just had that freedom to play the natural game that I play and take the bowlers on. It was one of those innings that sometimes comes off and sometimes doesn't."

Perry and McGrath put on a century stand for the fifth wicket, coming together with the tournament favourites 113 for 4, and both scored boundary-laden fifties after New Zealand's bowlers had kept a lid on Australia's run rate and toppled their top-three relatively cheaply, with Rachael Haynes' 30 the best of them. Gardner came in when Perry fell for 68 and proceeded to smash four sixes and four fours.

Then, a steady procession of New Zealand wickets, led by young quick Darcie Brown's 3 for 22 from seven overs - including two of their big three in Suzie Bates and Amelia Kerr for 16 and 1 respectively - ensured the hosts were never in the chase. Amy Satterthwaite then held one end up with a fighting 44 before being Gardner's first wicket. A second strike from the offspinner sealed victory for Australia, when Lea Tahuhu holed out to deep midwicket.

"I don't think I've ever seen Darcie bowl that well," Gardner said. "I think with the wind behind her, she was probably bowling five Ks quicker as well and it just seemed probably too fast for them at some points.

"She's got that raw pace and sometimes, scares batters into taking their wickets, but I think today, she controlled the ball beautifully. She bowled really nice out-swingers and a couple of times she was unlucky not to take the edge of Suzie's bat."

New Zealand, meanwhile, were lamenting what bowling coach Jacob Oram described as their first "blip" of the tournament, not counting the surprise loss to West Indies in the opening match by three runs which came down to some spectacular bowling and fielding by Deandra Dottin in the final over.

And he was looking for more consistency in the field from New Zealand, which against Australia was at times spectacular and at others, ordinary.

"We know that to go far in this tournament or to go far as a team full stop, we need to field as well and as consistently well as we can and at the moment, we're just a bit hamstrung by some mistakes which are not like us," Oram said.

"I can only put that down to a little bit of pressure, that is a big stage like the World Cup, and we saw a couple of instances today where balls got away from fielders and went to the boundary for four, which is uncharacteristic, but again, just potentially a by-product of these big stages."