Sydney: World champion Grant Hackett has withdrawn from a pre-Olympic clash with world record holder Kieren Perkins in the 1,500 metres freestyle, saying he was afraid of illness.

Hackett, 20, won the event at the Australian selection trials in Sydney in May in 14 minutes 46.35 seconds, with 1992 and 1996 Olympic champion Perkins second in 15:01.14.

The pair were to have met for the last time before next month's Sydney Olympics at a Grand Prix in Melbourne next weekend. Hackett said he would concentrate on the 200 and 400 metres in Melbourne, fearing a tough race in the 1,500 might push his immune system over the edge.

"Going from the warm weather on the Gold Coast to 12 degrees in Melbourne, it's really important that I look after my body and don't push myself too hard," Hackett said on Tuesday.

American Erik Vendt clocked 14:59.11 at the U S Olympic trials last Wednesday to jump from 25th in the world rankings to second in the 1,500, splitting the two Australians.

Perkins said on Tuesday he was still discussing with coach John Carew which events he would swim in Melbourne. He said that if he decided to race the 1,500 he would not attack it with full force. "It'll be a swim, not a race," Perkins said

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