The Clark County coroner's office says a security guard at the Flamingo hotel called police about 5:40 a.m. Sunday to report a person had apparently fallen onto a driveway.
John McCarthy was taken to a hospital, where he was pronounced dead at about 6:15 a.m.
Coroner's officials were conducting an autopsy Monday, but say determining McCarthy's exact cause of death could take weeks pending toxicology test results.
A group of 11 Port players left Adelaide, Australia on Saturday for a vacation in the United States.
McCarthy played in 21 matches in 2012 for Port Adelaide, which plays in the top-flight Australian Football League.