Trailing by 15 points after the first quarter, John Longmire's Swans stunned the Giants with a blistering second-half performance to claim bragging rights with a 14.14 (98) to 10.9 (69) triumph on Saturday in front of a 40,337-strong crowd at the SCG.
GWS had started brightly despite conceding the opener to James Rowbottom, slotting three unanswered goals to claim an early ascendancy in the opening term.
But Sydney started the second quarter with goals to Logan McDonald and Will Hayward (four goals), before torrential rain drastically changed conditions.
Will Hayward (c) celebrates one of his goals in the Swans' derby win over the Giants. (Dean Lewins/AAP PHOTOS)
The Swans adjusted best, limiting the visitors to just two behinds for the second term and taking with them a nine-point lead to the main break.
Jess Hogan, Brent Daniels and Darcy Jones kicked a goal apiece in the third quarter to keep the Giants in the game, but their hard work was undone by a starting position infringement in the dying seconds.
Tom Papley was able to score and leave GWS coach Adam Kingsley unable to contain his frustrations on the bench.
The Giants' famous 'big, big sound' was all but reduced to a whimper in the fourth term, with Chad Warner slotting the final nail in the coffin.
It was Errol Gulden (29 disposals, five clearances) who claimed the Brett Kirk Medal awarded to the best afield in Sydney derbies played at the SCG, the first time he has earned the honour.
GWS midfielder Callan Ward was earnest in his attempt to keep Isaac Heeney quiet but the early season Brownlow favourite registered 26 disposals and seven clearances regardless.
Heeney and Gulden were well-supported by Warner (28 disposals, eight clearances) and Rowbottom (two goals, 21 disposals), while Brodie Grundy (35 hitouts) took out the ruck battle against Kieren Briggs (23).
The pack flies for a high ball in the AFL's 27th home-and-away Sydney derby. (Dean Lewins/AAP PHOTOS)
Josh Kelly (24 disposals) and utility James Peatling (23) were the shining stars in a Giants midfield missing Stephen Coniglio (knee), while Daniels (two goals) and Hogan (two) led in attack.
GWS will have an anxious wait over the fitness of Tom Green after the midfield bull injured his ankle, leaving the ground in the first quarter and not to return after a Hayden McLean tackle on Finn Callaghan caught his left ankle.
Star goalkicker Callum Brown could be in trouble after laying a high bump on Tom McCartin in the second term, sending the key defender to ground before the Swans so after subbed him out.
McCartin has an unfortunate history with head injuries, missing seven games last season due to two separate concussions.
Veteran dSydney efender Dane Rampe stood tall in McCartin's absence and shone in his first game since returning from a hamstring injury, collecting a game-high 15 intercept possessions.
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