The Bryan brothers, both aged 38, announced their retirement from the men's international team event on Sunday.

Identical twins Mike and Bob - the most successful duo of all-time - helped USA to Davis Cup glory in 2007, having featured in the loss to Spain three years earlier.

"Mike and I want to formally announce our decision to step down from our role as active members of the US Davis Cup Team," the 2012 Olympic Games gold medal winners wrote via Instagram.

"Clinching the Davis Cup Final in 2007 while representing Team USA was one of the greatest highlights of our career. We've been blessed to play for two amazing captains, Patrick McEnroe and Jim Courier, and we are extremely grateful for their leadership and trust over these last 14 years. 

"Also, we'd like to extend our dearest gratitude to our fellow team-mates, USTA staff, our friends and family, and the passionate fans who have been there for us on this incredible journey. We are indebted to you all for your loyal support. 

"With love and appreciation, Bob and Mike."

Mike and Bob are in the third round of the men's doubles at the Australian Open in Melbourne.