Greater Western Sydney utility Harry Perryman is set to join Collingwood as an unrestricted free agent.
Perryman has shunned a long-term offer from Port Adelaide to join the Magpies in another blow to the Giants before the trade period opens.
"Harry Perryman has informed the club of his decision to explore his options as an unrestricted free agent," the Giants said in a statement on Tuesday.
"Perryman has selected Collingwood as his club of choice."
GWS have also lost Isaac Cumming, another unrestricted free agent, who will join Adelaide after also considering an offer from Port.
The Giants will receive draft-pick compensation for losing both players - depending on the size of the contract in monetary and length terms, the picks could be in the first-round.
Cumming, 26, played 81 games for the Giants in seven seasons while Perryman played 129 matches in eight seasons.
Perryman had long been linked to Port, who were understood to have offered about $850,000 a season for the 25-year-old.
But the Magpies swooped late with a similar cashed-up offer for the versatile utility who supported Collingwood as a child.
Collingwood coach Craig McRae has made clear to his list management team that he wants players, not draft picks, from the trade period.
"I'm a coach that wants to bring players in," McRae told SEN radio last week.
"It's such a hard market fishing from the same pond, but I don't want picks ... let's bring players in and make us better.
"We're somewhat deliberate on that and we think Harry can make us better."
The AFL's free agency period starts on Friday and runs until October 11 while the trade period opens on Monday and finishes on October 16.
