Jordan Spieth 'uncertain' about Rio participation amid Zika fears

World number two golfer Jordan Spieth has said he is uncertain about his participation in the upcoming Rio Olympics due to the increasing fears over the Zika virus.

The 22-year-old American also admitted to feeling added pressure especially in the wake of top-rated players pulling out of the Olympics in Rio de Janerio citing concerns over the Zika virus, the Guardian reported.

Spieth, a two-time major champion, however, added that he would weigh up all the issues before making a final decision.

Brazil has been most affected by the mosquito-borne virus that has spread rapidly through Latin America and the Caribbean. It is known to cause the head-shrinking microcephaly and other birth defects.

On Tuesday, world number one Jason Day joined a host of golfers to withdraw from this year's Olympics, which includes Rory McIlroy, Adam Scott, Louis Oosthuizen, Charl Schwartzel, Marc Leishman and Vijay Singh.

Explaining the rationale behind his decision, Day had stated that he was concerned about the possible transmission of the Zika virus and the potential risks it may present to his wife's future pregnancies and to future members of his family.

Golf, which is making its return in Olympics after a century-long absence, has now lost two of its biggest stars after the withdrawal of four-time major champion McIlroy last week.