AUCKLAND, New Zealand (AP)—Former world No. 3 David Nalbandian beat defending champion John Isner 6-4, 7-6 (3) on Thursday to reach the semifinals of the Heineken Open.

Nalbandian, the No. 6 seed in Auckland and the 27th-seed for next week’s Australian Open, beat the third-seeded American, who appeared to be troubled by an arm injury on Thursday.

The tournament’s top two seeds, Spaniard’s David Ferrer and Nicolas Almagro, also won through to the semifinals in three-set matches.

Nalbandian will play Almagro in the semifinals while Ferrer will take on unseeded Colombian Santiago Giraldo who beat the No.7 seed Thomaz Bellucci of Brazil 6-2, 6-4.