A suspected ACL injury to breakout defender Jack Buckley has soured GWS's best win of the AFL season.
The Giants inflicted Melbourne with their first defeat at the MCG this year, upsetting the ladder-leaders by nine points on Saturday.
GWS coach Leon Cameron hailed the performance, which saw the Giants leapfrog Richmond into eighth, but was left upset for Buckley's likely season-ending injury.
"We're probably fearing the worst," Cameron said.
"He's off at hospital having some scans. It's just heartbreaking sometimes when you see these injuries, especially for a kid that has put so much into his footy over the last few years.
"He's come from being a rookie, to being a bona fide AFL player who holds down a key position in the backline.
"He's a really popular kid and that's the heartache - the emotion and the joy of winning at the MCG against a great team, then five minutes afterwards you realise you've lost one of your great young fellas."
Buckley, 23, had played just two games heading into this season but has played all 15 matches this year.
After starting the season 0-3, the Giants are back in finals contention at 7-1-7, even with a draw against North Melbourne and a defeat to fellow strugglers Hawthorn last week.
