This file photo taken on December 05, 2015 shows Michael Phelps swims in the 200 Meter Butterfly finals at the AT&T Winter National Championships at the Weyerhaeuser King County Aquatic Center in Federal (AFP)
Swimming legends Michael Phelps and Grant Hackett have been training together and swapping tips about their "ups and downs" as they target next year's Rio Olympics.
Dual Olympic champion Hackett, 35, has come out of six years of troubled retirement to try to make Australia's team for Rio next year, and has just spent three weeks training with Phelps under coach Bob Bowman in Arizona.
He also trained with American stars Ryan Lochte and Missy Franklin, who gave him a crash course in cutting-edge techniques in the sport, The Australian newspaper reported.
Hackett, who retired in 2008 after winning the 1500m freestyle at both the 2000 Sydney and 2004 Athens Olympics, and claiming four world titles in the event, said he found his time with Phelps particularly beneficial.
"I really, really enjoyed that. It was nice to go somewhere and have a single focus and sit in there and see how they approach training," he told the broadsheet.
"I stayed with Michael for some time. He's been through his ups and downs as I have and we talked very candidly about those things. He's a very insightful character."
The toned and fit-looking Hackett said his level of focus felt like he was approaching his first Olympics again.
"When I look at my birth certificate I know it's not my first Olympics but this campaign is also like a rebirth for me. I have come back to it with a totally different perspective," he said.
"The last three times I went to the Olympic trials I was already thinking about winning the Olympics, not about making the team."
He added that spending time with America's Phelps, the most decorated athlete in Olympic history, had left him "confident that I can get back to where I want to be".
Hackett will now return to his regular training group on Australia's Gold Coast under coach Denis Cotterell, determined to be at the top of his game for the Olympic trials in April.
"When you see the intensity that Michael Phelps approaches his training with, the expectation he places on himself, you want to make sure you go back and do everything right," he said.
"That's given me more clarity about what I need to do to be competitive."
Both Hackett and Phelps, widely seen as two of the greatest swimmers ever, have endured troubled times in recent years.
Hackett's life after swimming quickly ran into problems with a messy divorce and allegations he smashed up his Melbourne apartment, while 18-time Olympic gold medallist Phelps has battled alcohol issues.
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