MELBOURNE, Australia - At 32 years old, Hsieh Su-Wei is proving to be a dangerous floater at Grand Slam tournaments, backing up her Roland Garros upset over Johanna Konta with a 7-6(1) 6-4 victory against No.3 seed Garbiñe Muguruza at the Australian Open.

"It's never easy to play against top 20 girls," Hsieh told the press afterwards. "I do a little bit better today and try to hang in there. I know the weather is going to be a little bit tough today because I hear weather is going to be over 39 degrees. I was thinking, 'Ah, I'm from Asia. I maybe can handle it better than other girls.'"

Hsieh raced to a 5-2 lead to start the match, and while Muguruza fought back to level the opening set, had few answers in the ensuing tie-break; an identical lead in the second proved a bridge too far for the Spaniard and Hsieh served out the upset on her second match point.

Muguruza briefly became WTA World No.1 shortly after winning her second major title at Wimbledon, but physical issues have stunted her start to 2018, retiring from the Brisbane International due to leg cramps and withdrawing from the Apia International Sydney after feeling abductor pain in her first match.

"She's definitely a very tricky opponent, and even more if she plays well," Muguruza said in her post-mach press conference. "I think today she played well.

"I maybe could have done things better, but at the end, she deserves to win. That's really it."

A quarterfinalist at last year's Australian Open, Muguruza took a medical timeout for blisters during the match, but didn't feel physical issues contributed to the defeat.

"I was wrapped and with a lot of taping, but just to try to make it better.

"I was pretty happy, because I didn't run a lot today, I didn't really feel it. It was getting to the process of really recovering. That's it."

The Taiwanese veteran peaked at No.1 atop the WTA doubles rankings back in 2014, but has proven more that capable on the singles court, ranked as high as No.23 in the world. She broke through on the major stage all the way back in 2008, when she made it to the fourth round of this very tournament as a qualifier.

"I think tennis is more about the mental[ity]," said Hsieh. "So it was helping each other, like, when I played better in singles, when I go on doubles court, I feel my baseline is better."

"I was doing a lot of different training," Hsieh continued. "I do the topspin, I mean, the flat balls and slice. I try to practice all the stuff. So against different player, I try to do a little bit different stuff. Not try to play the same game. So it helps a lot."

Striking clean groundstrokes with two hands on both sides, she hit 25 winners to just 23 unforced errors; the always aggressive Muguruza struggled to find her range throughout the one hour, 59 minute encounter, with 43 unforced errors negating her 29 winners.

Hsieh will take on former World No.2 Agnieszka Radwanska for her first Grand Slam fourth round in 10 years; Radwanska rallied from a set and a break down to defeat Lesia Tsurenko, 2-6, 7-5, 6-3.