Bob and Mike Bryan are the latest top tennis stars to have withdrawn from this summer's Olympics in Rio de Janeiro, citing fears over the Zika virus.
The American doubles pair had been expected to defend their gold from London 2012 at this year's competition but said they had decided to pull out after "countless hours of deliberation".
"Though we'd love to compete again, as husbands and fathers, our family's health is now our top priority," the brothers said in a post on social media.
"Representing Team USA is one of our proudest tennis moments to date and winning Gold in 2012 will always remain the pinnacle of our career. The Olympics means so much to us for so many reasons and the memories we have wearing the Stars and Stripes will burn brightly forever.
"Thank you to the USTA for the nomination and to our fans for their unwavering support. We wish every athlete luck in their quest for Olympic glory and hope the Rio games are a positive experience for everyone involved."
Other top tennis players to have withdrawn over Zika concerns include Milos Raonic, Tomas Berdych and Simona Halep.
