The restricted free agent has until Dec. 1 to agree to an NHL contract or he will have to sit out the entire 2017-18 season.
Athanasiou has not signed a contract with the Swiss club, though by sitting out a year he would likely be in contention for a spot on Canada’s Olympic roster.
“He called me (Friday) just to say that he is going to Europe,” Red Wings general manager Ken Holland told The Detroit News.
The 23-year-old is one of the fastest players in the game but has struggled to find consistent ice time in coach Jeff Blashill’s lineup.
Detroit is up against the cap and signed forward David Booth to a one-year contract on Monday.