Athens Olympic hammer throw champion Koji Murofushi has pulled out of this weekend's IAAF Grand Prix meet in Osaka after failing to fully recover from illness, athletics sources said Thursday.

Murofushi, awarded victory in Athens after Hungary's Adrian Annus was disqualified for doping violations, was set to open his season at Nagai Stadium on Saturday but his preparations were slowed when he was struck down with a fever last week and will sit out the meet.

Murofushi is expected to make his first appearance of the season at the national championships in Tokyo in June, which doubles up as a qualifier for the athletics world championships in Helsinki in August.