Bryan twins putting health first

Bob and Mike Bryan will not defend their Olympic tennis doubles title in Rio de Janeiro, citing health concerns.

The American twins announced their withdrawal on Facebook on Saturday, saying that as "husbands and fathers, our family's health is now our top priority."

They didn't mention the Zika virus, which has been linked to birth defects and been cited by several athletes in tennis and other sports who opted to skip the Summer Games that open on Friday in Brazil.