By Ian Ransom


MELBOURNE (Reuters) - Former champion Angelique Kerber was driven to distraction by the unorthodox game of world number 88 Hsieh Su-wei but overhauled the Taiwanese battler 4-6 7-5 6-2 to reach the quarter-finals of the Australian Open on Monday.


The 21st seed was being tied up in knots by double-sided Hsieh's angles and slices in a match of clashing styles at Rod Laver Arena before the slender Taiwanese fatigued and the German's power game prevailed.


Hsieh saved two match points to hold serve in a late burst of resistance but 2016 champion Kerber closed it out in the next game when she whipped an easy passing shot.


Kerber, 30, will meet American Madison Keys for a place in the semi-finals.


(Editing by Peter Rutherford)