Top seed David Ferrer booked his quarter-final place in Auckland as he eliminated Yen-Hsun Lu in three sets 6-4 2-6 6-3.
Ferrer, who got beaten by Nikolay Davydenko in the semis in Doha last week, could become the first player since Roy Emerson to win this tournament four times.
In the last 8, the Spaniard will square off against Slovak Lukas Lacko, who dismissed no.8 seed Thomaz Bellucci of Brazil 6-3 7-5.
Also through to the quarters is German veteran Tommy Haas, seeded third at this year’s tournament. Haas made fairly light work of the Dutch qualifier Igor Sijsling, prevailing 6-4 6-3 in just over an hour.
One of the most pleasant comebacks is Frenchman Gael Monfils, who got awarded a wild card to enter the competition. Monfils advanced into the last 8 after overcoming Australian qualifier Greg Jones in straight sets 6-4 6-2.
The Frenchman was suffering from various injuries last year and had to skip several tournaments. He will face Haas next.