* Australian golfer says fears for wife's health * Olympic Committee supports decision * Leishman was top-ranked candidate to join Day (Recasts, changes dateline, adds Australian Olympic Committee statement) SYDNEY, May 5 (Reuters) - Golfer Marc Leishman said on Thursday he has withdrawn his candidacy for the Rio Olympics, citing the Zika virus and health concerns for his wife, becoming the first Australian athlete to withdraw over the mosquito-borne virus. Leishman, Australia's number three golfer, was first in the race to qualify for Rio alongside compatriot and world number one Jason Day after former U.S. Masters champion Adam Scott ruled himself out of the tournament last month. More...