Michael Phelps has confirmed that he will compete at the Olympics for the final time on Saturday before retiring for good.

The 31-year-old - the most decorated Olympic athlete in history - previously retired after London 2012 but reneged on his decision two years later in order to compete in Rio.

That decision proved to be a fruitful one as he increased his haul by four golds and one silver for a career total of 27 Olympic medals, including 22 golds.

Phelps will bid for one last gold on Saturday as part of the USA 4x100 medley relay team and, speaking to reporters in Rio on Friday, he confirmed that the event will be his swansong.

"[I'm] done," he said. "Chad [le Clos] asked me in the award area and the Dwyers were chanting 'four more years'. They did the same thing in London. The 800m free relay guys said four more years. No. I am not going four more years and I'm standing by that.

"I've been able to do everything I've ever put my mind to in this sport. And 24 years in the sport, I'm happy with how things finished. Being able to close the door on this sport how I want to, that's why I'm happy now.

"I'm ready to retire. I'm happy about it. I'm in a better state of mind this time than I was four years ago. And yeah, I'm ready to spend some time with [baby son] Boomer and [fiancee] Nicole. No more. This is it. I said it a bunch before. But I'm not doing it. No more. I swore in London I wasn't coming back and this is final. Were the papers here, I'd sign them tomorrow."

Phelps was speaking after sharing an unusual three-way tie for silver in the men's 100m butterfly.