MIAMI, FL, USA - Fresh off her second win over a reigning World No.1, Hsieh Su-Wei ended the hopes of a former World No.1 at the Miami Open, the No.27 seed coming through 6-3, 6-7(0), 6-2 against No.13 seed Caroline Wozniacki to reach her first quarterfinal at Premier Mandatory level.

In four previous meetings with the Dane, Hsieh had won just one set - but they had not played since the 2015 Kuala Lumpur semifinals, two years before the Chinese Taipei player became a bona fide upset artist: all six of the 33-year-old's career Top 10 wins have come since 2017, when she added coach and boyfriend Frederic Aniere to her traveling team, starting with her defeat of Johanna Konta in the first round of Roland Garros that year and including Saturday's stunning upset of Naomi Osaka.

Read more: 'I just let her be herself' - Hsieh forms perfect match as boyfriend doubles as traveling coach

Hsieh's belief in her ability to pull off her fifth Top 20 win of the year was evident throughout a confident first set, during which she thoroughly out-manoeuvred the 2018 Australian Open champion from every corner of the court. The Hiroshima champion is renowned for her idiosyncratic use of touch and finesse, but it was her flat hitting that characterized her strategy today: aggressive returns taken as early as possible to steal time from Wozniacki, raking down-the-line groundstrokes of extraordinary precision that found a way through one of the game's best defenders.

Not everything was smooth sailing for Hsieh: an early break lead and two points for 4-1 slipped as two double faults and two rare errors enabled Wozniacki to level at 3-3. But the Auckland and Dubai semifinalist hit back in a four-deuce game, conjuring up a jaw-dropping lob at full stretch and clever wrong-footing groundstrokes while taking advantage of the former World No.1's shakiness in the forecourt. Two games later, Hsieh broke Wozniacki once more to take the opening act on her fourth set point.

The Eastbourne and Beijing champion began the second set more positively, with emphatic net work leading to a 3-1 lead. But once again, Hsieh was able to find another level: her most creative spell of play saw the former doubles World No.1 reel of four of the next five games, showing off her hand skills with some astonishing redirected winners to stave off a 1-4 double break deficit and to level at 3-3. As the set reached its climax, Hsieh seemed increasingly able to simply place winners delicately in the corners, as well as bringing out some of her trademark dropshot-lob magic to delicious effect.

But just as Hsieh was poised to ride her purple patch to victory, twice coming within two points of the win at 5-4 on Wozniacki's serve, the 2017 Miami finalist's trademark stubbornness came to the fore. 

Read more: 'Sometimes you just need to fight' - Healthy Wozniacki in high spirits after Miami Open return

Approaching the net on her own terms, the 28-year-old managed to hold by outdoing Hsieh in a cat-and-mouse exchange - and from 5-6 down, Wozniacki cantered through 11 of the set's final 12 points, including a tiebreak whitewash, with brave volleying as Hsieh's touch and accuracy deserted her.

Having dramatically turned the tables on her lower-ranked opponent, momentum entering the deciding set was firmly with Wozniacki. But it was Hsieh who came back out rejuvenated, once again meticulously steering the ball from line to line and conjuring up perfect winners from defensive positions.

Indeed, Hsieh would avenge her run of lost points at the end of the second set with a streak of 11 of her own to open the third, part of another spellbinding patch that found her drop only two points en route to a 4-0 lead. As she maintained her lead, her tennis became even more breathtaking: a combination of dropshot, lob, sliced smash and angled volley in the sixth game, no shot hit with any pace, was exhibition-level trickery.

Two solid holds from Wozniacki ensured that Hsieh would not be able to simply cruise to victory, but when called on to serve the match out for the first time, the 33-year-old stepped up to the task magnificently, with three more winners - including a pass at full stretch on her first match point - taking her tally for the day to 33 after two hours and 13 minutes.

Last month, a run of upsets to the Dubai semifinals sealed Hsieh's biggest ever run at a Premier 5 event - and now she's proving herself at an even higher level. The 2019 Miami Open has been fertile ground for finesse players so far - as well as Hsieh carving up her section, Monica Niculescu scored an upset over No.20 seed Garbiñe Muguruza, while Tatjana Maria and Yulia Putintseva are still alive in the bottom half after stunning Sloane Stephens and Belinda Bencic respectively. For Hsieh, in particular, it might be time to stop talking of the World No.27 as an upset artist - and maybe start accepting her as a legitimate threat.