Former champion Angelique Kerber battled back against world number 88 Hsieh Su-Wei to reach the Australian Open quarter-finals.
Kerber, the favourite for the title following her convincing win over Maria Sharapova in round three, recovered from a set down to win 4-6 7-5 6-2.
The 30-year-old German and 21st seed is the last remaining Grand slam champion in the women's singles draw.
She will play American 17th seed Madison Keys in the last eight.
Despite breaking serve in the first game, 2016 champion Kerber struggled in the first half of the match as the unconventional Hsieh, who plays with a double-handed backhand and forehand, hit 20 winners in the first set alone.