Adelaide Crows defender Phil Davis has become the first player to join the new AFL franchise Greater Western Sydney from an existing club.

The 20-year-old player has played just 18 games with the Crows.

He said money was not the only factor behind his decision to move.

Adelaide football operations manager Phil Harper said they had offered him great financial incentives to stay at the club, but Davis said that the opportunity to start a new franchise along with all its challenges, had been a great lure to him, on top of the money.

Harper said they understood his decision to leave, but were disappointed by it.

It's the second blow of this nature to hit the Crows after losing backman Nathan Bock to the Gold Coast last season.

GWS are allowed to recruit a maximum of one uncontracted players from each of the other 17 clubs over the next two seasons.