Five-time Olympic champion Ian Thorpe's of Australia return to competitive swimming after a 15-month break lasted only one race at the World Cup meet in Sydney.

The Australian star withdrew from the event Saturday due to illness after clocking the fastest time in the qualifying race for the men's 100-meter freestyle earlier in the day (47.87 seconds).

Australia's coach, Alan Thompson, said Thorpe had not been feeling well all week, and had missed some training sessions.

Thorpe took an extended break from competition following the 2004 Athens Olympics.