Port Adelaide footballer John McCarthy fell to his death at a Las Vegas hotel after being separated from his AFL teammates on an end of season trip.
Witnesses watched McCarthy fall from the hotel building about 5.40am Sunday, Las Vegas time, in a fatality which has devastated the AFL.
The AFL and Port remain puzzled at the circumstances of the death of the 22-year-old, who was found on a driveway at the Flamingo Hotel - not the hotel where he was staying.
"We understand that there are witnesses on the ground at the incident, but we have no details at this point," Port chief executive Keith Thomas told reporters in Adelaide on Monday.
"My understanding is that he fell from a building but I don't have any more detail than that."
The Victorian-born McCarthy was in Las Vegas with 10 other Port players, who were unaware their teammate had died until contacted by the club.
"They weren't with John at the time, and it was a great shock," Thomas said.
The stunned players would return to Australia as soon as possible, while some of McCarthy's teammates at Port Adelaide and his former club Collingwood broke down when told of his death.
"Today's news is met with utter devastation, the players are shattered," Collingwood president Eddie McGuire told reporters in Melbourne.
"To lose a player of his character and his wonderful personality, it's heartbreaking for all of us."
McCarthy left Collingwood, where he played 18 games over four seasons, late last year and joined Port Adelaide, where he played 21 games this season.
"John was a very popular Port Adelaide player who had embraced the club as we had embraced him," Thomas said.
"He's a fantastic young fella, well-liked.
"He came into our footy club looking to reignite his career, he played 21 of the 22 games this year, started like a bomb and looked fantastic - we had great hopes for him."
A Flamingo Hotel spokeswoman said McCarthy was found unresponsive on a hotel driveway.
He was taken to the University Medical Center of Las Vegas, where he was pronounced dead.
The Nevada Clark County Coroner's Office is investigating McCarthy's death while Port players, coaches and staff were offered counselling.
"We'll pull together, the players will pull together - they're all together now, and it will strengthen us," Thomas said.
McCarthy became the first AFL footballer to die while still playing since Melbourne's Troy Broadbridge was swept out to sea by a tsunami while honeymooning in Thailand in 2004.
McCarthy died in a city renowned as a trouble spot for holidaying AFL players.
In 2004, ex-North Melbourne captain Wayne Carey spent a night in a Vegas jail after being arrested for a misdemeanour allegedly involving his then-wife. The local District Attorney elected not to pursue the case.
And in 2006, former West Coast player Chad Fletcher reportedly stopped breathing after choking on his vomit in Las Vegas. Fletcher was revived and taken to hospital, where he spent four days.
AFL chief executive Andrew Demetriou described McCarthy's death as "terribly sad".
"To lose a young man at the age of 22 who was in the prime of his life is tragic," Demetriou told reporters in Melbourne.
AFL Players' Association chief executive Matt Finnis said McCarthy quickly won respect for his "fearless attack on the contest" while several rival AFL clubs expressed sympathy to McCarthy's family.