The German top seed, who needed three sets in both of her opening two matches, won 6-0 6-4 in Melbourne.

Kerber faces Coco Vandeweghe in round four after the American beat Canada's Eugenie Bouchard 6-4 3-6 7-5.

Venus Williams, 36, thrashed China's Duan Yingying 6-0 6-1.

Russian eighth seed Svetlana Kuznetsova was another winner early on day five, needing three hours and 36 minutes to beat Serbia's Jelena Jankovic 6-4 5-7 9-7.

"Jelena was in total control in the third set but I was trying to hang in, it was amazing that I could turn it around," said Kuznetsova, who trailed 3-0 in the final set.

"I just waited and tried to recover some breaks. I was not playing my best."