Alex Rowe has pulled out of next month's World Athletics Championships in Beijing.
The 23-year-old, who equalled the Australian national record over 800m last year, has cited a lack of form as the main reason behind his withdrawal.
"My recent race results have made it clear that I am not in the shape expected of an international athlete and consequently it was evident that this was the best decision," he said in a statement.
The omission of Rowe has made Jeff Riseley Australia's sole representative in the men's 800m in China.