The fourth time was the charm for Danielle Collins, who scored her first win over a reigning World No.1 in the second round of the Adelaide International by taking Ashleigh Barty out 6-3, 6-4 in just 62 minutes.

Collins had lost to Barty in all three of their previous meetings, including a 3-6, 6-1, 7-6(5) semifinal in Adelaide last year, but on Wednesday recovered from a break down in both sets to reel off the last five games of each. The result extends the American's record in 2021 to 9-3 following a quarterfinal at the Yarra Valley Classic and a semifinal last week at the Phillip Island Trophy. 

"I think I was really familiar with her game after losing to her three times," said Collins afterwards. "So I certainly got some great tennis lessons out of that and have learned from it."

Collins also attributed her fine run of results to improved fitness as a result of last year's Tour shutdown.

"My physical fitness is one of the things that has improved a lot, because we had such a long period of being able to train consistently for weeks and weeks and months and months," she explained. "I think pretty much from February to July I didn't play a tournament, and then I had a nearly three-month pre-season. So I think my overall physical fitness and strength has gotten a lot better, and that gives me more confidence when I go into long points and I'm being a little bit more patient within the rallies.

"My serve has improved a bit as well - I'm starting to get a few more free points here and there on my serve. That was something that I really worked on a lot during the off-season. I've had some days where it hasn't been as great, but I just try to get back to it and what I've been working on. I think those are probably the three biggest areas that I've improved the most."

Both players had spells in which they dominated play. Defending champion Barty began both sets with her serve clicking: seven of her first eight went unreturned as she went up 3-1.

Collins had dropped serve in the opening game following a controversial linecall, and the initial stages of each set were error-strewn from the World No.37. But Barty was unable to sustain her serving level through the end of either stanza, beckoning her opponent back into the contest with a trio of double faults - something she bemoaned afterwards.

"I made one first serve in that game, just gave her a look back into the match," Barty recalled. "It's just disappointing, I think, to have two sets in a row where I went on a run of losing games."

2021 Adelaide Highlights: Collins ousts Barty

By contrast, Collins was able to rein in her power sufficiently to emerge with a ratio of 20 winners to 15 unforced errors. Raking the ball from side to side and landing her returns deep at Barty's feet, she was in full flow as she flipped momentum thoroughly. Having lost 11 out of 12 points to fall behind 1-4 in the second set, Collins managed to reel 20 of the next 23 to accelerate over the finishing line.

In the quarterfinals, Collins will face No.5 seed Iga Swiatek, who was superb in almost every area in dispatching qualifier Maddison Inglis 6-1, 6-3. The Pole slammed 26 winners and blended power and finesse throughout to return to the last eight of a tournament for the first time since her Roland Garros title last October. 

Swiatek's first serve percentage was the only area of concern - not that it proved a significant obstacle. Despite landing only 46% of her first deliveries, the 19-year-old only faced break points in one game, as she attempted to serve out the first set, and saved both with unreturnable serves.