Giants earn their second win of the season after just three rounds.
Greater Western Sydney showed it can grind out a win in tough conditions with a 32-point victory over struggling Melbourne on Sunday.
The Giants led for most of the game apart from a short period in the third quarter, on their way to a 10.19 (79) to 7.5 (47) victory at the Sydney Showgrounds.
Leading by just one point early in the final quarter, GWS slammed on four straight goals through two to midfield rookie Josh Kelly and one each to ruckman Shane Mumford and small forward Devon Smith.
The result improved their record to 2-1 and left Demons coach Paul Roos still looking for his first victory after three defeats.
Melbourne became the first team to lose twice to the Giants, who have already equalled their previous best season win tally of two.
On a damp and wet afternoon the two teams kicked just three goals between them in the first half in a wet weather arm wrestle.
Kelly and key forwards Jeremy Cameron and Jonathon Patton each kicked two goals for GWS.
Jack Watts and Lynden Dunn each booted two goals for the Demons.
The Giants led 33-17 in the second quarter, but three straight goals to Melbourne gave them a very brief lead.
GWS hit back to lead by seven at the last change, only for a James Frawley major to cut the deficit to one early in the final term.
Midfielder Adam Treloar revelled in the wet, piling up 33 possessions and laying 14 tackles.
The Giants enjoyed a 61-36 advantage in clearances and finished 79-37 ahead in hit-outs, with Mumford tallying 60 of the latter.
Greater Western Sydney: 10.19 (79) – J Patton 2, J Cameron 2, J Kelly 2, A Treloar, S Mumford, D Smith, S Coniglio
Melbourne Demons: 7.5 (47) – J Watts 2, L Dunn 2, D Kent, J Frawley, M Jones