Sydney, Jan 15: Juan Martin Del Potro's Sydney International title defence is over after the Argentine lost to Kazakhstan's Mikhail Kukushkin in straight sets Thursday.

Del Potro, who was playing only his third match in nearly a year after a career-threatening wrist injury, lost 7-6 (5), 7-6 (3) at the Sydney Olympic Park.

The former US champion, whose ranking slipped to 338 while he was recovering from major surgery, had enjoyed an encouraging first two rounds on the comeback trail, taking down Ukraine's Sergiy Stakhovsky and the top seed Italian Fabio Fognini.

IANS