Melbourne - Angelique Kerber kept her hopes of a second Australian Open title alive with a battling come-from-behind 4-6, 7-5, 6-2 victory against Taiwan's tenacious Hsieh Su-wei on Monday.
Germany's Kerber, the 21st seed, will play Madison Keys for a place in the semi-finals after the American 17th seed steamrollered French eighth seed Caroline Garcia 6-3, 6-2.
Results from the Australian Open on Monday:
Tomas Berdych (CZE x19) bt Fabio Fognini (ITA x25) 6-1, 6-4, 6-4
Madison Keys (USA x17) by Caroline Garcia (FRA x8) 6-3, 6-2
Angelique Kerber (GER x21) bt Hsieh Su-wei (TPE) 4-6, 7-5, 6-2