Former great Hackett in rehab - manager
Grant Hackett of Australia is seen after competing in the men's 1500m freestyle at the 12th FINA World Championships in Melbourne, on April 1, 2007 - by Torsten Blackwood
Hackett, who won the 1,500m freestyle at both the 2000 and 2004 Olympics and claimed four world titles in a dominant decade at the top, jetted to the United States on Tuesday, apparently to begin rehabilitation.
It comes just weeks after fellow Australian swimming star Ian Thorpe entered rehabilitation for depression after a mixture of painkillers and anti-depressants left him disoriented on a Sydney street.
"Grant is currently in transit to seek treatment for a dependency to Stilnox medication," his manager Chris White told News Limited papers, referring to the sleeping tablets.
"His family and friends are enormously proud of his courage in pursuing this course of action."
However, on arrival in Los Angeles, Hackett told waiting Australian media that he was in the United States for a "retreat".
"No, I'm not calling this rehab whatsoever," he said. "This is a retreat, to get away for a while, to recharge the batteries which I have been planning for some time."
His father Neville said his son was "in denial".
"I think Grant is a little bit in denial, he thinks he just needs a bit of a recharge and a rest," Neville Hackett told Sydney radio station Triple M.
"I'd say rehab is certainly something that's needed there."
He added that his son would not be able to "fool the experts for long", saying that family had sought help for him recently.
"I would suspect Stilnox but I can't be a 100 percent sure," he said when asked what the main issue was.
Hackett's decision to leave Australia came just days after he was photographed in the early hours with only a singlet around his waist in the foyer of a Melbourne hotel, searching anxiously for his four-year-old son.
The former great, 33, retired from the pool in 2008 and has worked for the Nine Network and Westpac Bank since then.
But his reputation took a huge hit after he trashed his apartment in an alcohol-fuelled rampage in 2011 that saw his wife leave him.
The lanky Queenslander burst onto the scene at the 1998 world championships in Perth as a 17-year-old, where he lost the 400m final to a 15-year-old Thorpe.
The pair went on to help Australia's swimming team to the nation's best run of success since the golden days of the late 1950s and early 1960s.