Kerber kicked off her 2012 with a semifinal showing last week in Auckland, lifting her ranking to No.31 - just two spots short of her career-high. After yielding six games in her first round victory over Elena Vesnina on Monday, she beat Errani even more soundly, 61 62.
Next up for the fourth-seeded Kerber is Sorana Cirstea, a 26 63 75 winner over Bethanie Mattek-Sands in the match of the day. Cirstea rallied from a 62 32 deficit and was also down a break at 3-1 in the third.
Another quarterfinal will see No.1 seed Yanina Wickmayer play Simona Halep. Wickmayer disposed of wildcard Casey Dellacqua, 61 61, and Halep beat fellow Romanian and No.8 seed Irina-Camelia Begu, 64 62.
Advancing to her first quarterfinal since Moscow in October 2010 was 2007 Hobart champion Anna Chakvetadze, who raced out to a 5-0 first set lead in her 63 62 triumph over Tsvetana Pironkova. The Russian is playing in her first tournament since Wimbledon last year because of an inner ear inflammation that caused dizziness.