Title favourite Kerber thrilled to find answers in difficult test
Angelique Kerber was bamboozled but not beaten by Hsieh Su-wei as the title favourite battled into the quarter-finals.
Hsieh plays a different game from most, relying not on power but a mixture of spins and slices and ball placement to drive opponents to distraction.
Her scalps in Melbourne already included Wimbledon champion Garbine Muguruza and Agnieszka Radwanska, but 2016 champion Kerber has confidence after her unbeaten start to the season and kept her composure to win 4-6 7-5 6-2.
Kerber said: "I was always like, 'This is impossible' how she hit the ball. All the time she had the better answer. I'm happy about how I was able to change the match and played good tennis."
In the last eight Kerber will face US Open finalist Madison Keys, who blasted past eighth seed Caroline Garcia 6-3 6-2.
The 22-year-old's first Grand Slam final experience in New York last summer was a horror show as she won just three games against Sloane Stephens.
"To have such a great two weeks and then have it end the way it did, it was devastating," said Keys. "I want to put myself in the same position again so I can have a different outcome."
World No.1 Simona Halep eased into the quarter-finals with a 6-3 6-2 victory over Naomi Osaka and will now face sixth seed Karolina Pliskova, who had a 6-7 (5-7) 6-3 6-2 victory over fellow Czech Barbora Strycova.