GWS have pipped Essendon by two points at Giants Stadium, where Kyle Langford threatened to snatch victory after kicking two goals in the final two minutes of a dramatic AFL clash.
The Giants started strongly, steadied after a second-quarter slump then held on during a frantic goal-laden finish to triumph 16.11 (107) to 16.9 (105), making it four wins in five weeks for Leon Cameron's side.
The Bombers led briefly after Peter Wright booted an opening-minute goal then conceded six consecutive majors as they struggled to deal with the home side's rapid ball movement.
Essendon, having woken up at dawn to ensure they could fly in and out of Sydney on the same day because of the city's recent COVID-19 cases, responded with multiple epic comebacks.
The visitors, who were forced to substitute star Jake Stringer in the third quarter because of a leg injury, finished strongly and kicked four of the game's final five goals.
But they ran out of time, with Langford's third of the game coming with just four seconds remaining in the match.
A contentious umpiring call to not award key forward Cale Hooker a free kick in the final stages is already being hotly debated among pundits.
Langford also trimmed GWS's buffer to two points with two minutes remaining, only for GWS midfielder Jacob Hopper to nail a snapped goal that effectively secured the four competition points.
Jeremy Finlayson proved sinner and saviour for the home side.
He supplied two steadying goals in a dominant third term, stepping up alongside Toby Greene.
Finalyson's composed third quarter was in sharp contrast to his undisciplined elbow in the first quarter.
The key forward was reported for felling Zach Merrett after the midfielder kicked the ball, meaning he is at risk of missing the Giants' round-nine clash with Richmond at Marvel Stadium.
"One week for dumbness," Gerard Healy quipped in the Fox Sports commentary box.
Stand-in skipper Greene had a hand or foot in the majority of his side's most impressive moments, teeing up a couple of goals and kicking two himself.
Veteran Callan Ward also starred on the day he became GWS's all-time games record holder, while defender Sam Taylor's game-high 12 intercepts were also decisive.
GWS midfielders Ward, Tim Taranto, Josh Kelly and Tom Green tallied a combined 110 disposals, while Essendon on-ballers Merrett and Darcy Parish were also dominant.
