Melbourne: Former world No. 1 Angelique Kerber on Monday defeated Taiwan's Hsieh Su-wei 4-6, 7-5, 6-2 in the Australian Open round of 16 to qualify for the quarterfinals.

With her six breaks from 13, the 30-year-old German won in two hours and eight minutes over 88th-ranked Hsieh, who knocked out Spanish third seed Garbiñe Muguruza in the second round, reports Efe. "In these moments I'm just trying to stay focused. I tried to forget about the score and play every ball," Kerber said.

Winner of the title in 2016, Kerber, who is now ranked 16th, is due to play US' Madison Keys, who knocked out eighth seed Caroline Garcia 6-3, 6-2. "It's another tough match but it's the quarters now. I'll just try to continue focusing on my game. Madison is a tough opponent, but I'm feeling good here. I just want to enjoy it," Kerber explained.