North Melbourne has lost its fourth straight game, defeated by the Giants at Etihad Stadium on Saturday night.
The Kangaroos took it up to the Giants on Saturday night after a tumultuous week in which Harvey, Drew Petrie, Michael Firrito and Nick Dal Santo were told they wouldn't continue with the club next season.
GWS led by 11 points at the main break and set up the 14.16 (100) to 9.9 (63) win with a four-goal-to-one third term, defeating the Roos for the first time in six meetings.
The win leaves the Giants in third place on the ladder, but can only drop as low as fourth if Hawthorn beats Collingwood on Sunday and leapfrogs GWS and Adelaide. A fourth-placed finish from the Giants would see them matched up in a mouth-watering derby against cross-town rivals the Sydney Swans.
With leading Giants goalkicker Jeremy Cameron well held by Robbie Tarrant on Saturday, Jonathon Patton led the way in attack with five goals, while Steve Johnson added four in typically eye-catching style.
Harvey, who was the Roos' best player with 26 possessions and two goals, waved and clapped the crowd after the final siren in a show of appreciation before he led his team off the ground.
The Roos, who were top of the ladder after 12 rounds, couldn't move out of eighth place regardless of the result, but take worrying form into an away elimination final having lost their past four games, and won two of their past 11.
The Kangaroos' cause wasn't helped by influential defender Jamie Macmillan departing the game in the first quarter due to a hip injury.
Coach Brad Scott said the Kangaroos had work to do in the next two weeks to "rediscover what makes us a really good side".
"There were some OK things tonight, but we were far from our best," Scott said.
"We're winning enough of the ball and we're doing some things reasonably well, but we've got some work to do on our scoring efficiency, that's for sure.
"We're not scoring well enough at the moment … we've got a really good chance now with a couple of weeks to do some solid work on that."
MEDICAL ROOM
North Melbourne: The Kangaroos took a no-risk approach with Jamie Macmillan after a knock to his left hip in the first quarter. After a discussion about putting him back on, the decision was made to put him on ice, Scott said, saying he would be fine for the opening final in two weeks. Luke McDonald and Shaun Higgins got through their return matches well.
Greater Western Sydney: The Giants were sore post-match, Cameron said, and midfielder Lachie Whitfield would need the two-week break to recover from a suspected rib injury. The classy 22-year-old played through pain and finished with 20 possessions.
NEXT UP
North Melbourne will travel to Adelaide to take on the Crows if Hawthorn beats Collingwood on Sunday. If there is an upset, the Roos will travel to Perth to face West Coast. For GWS, a Hawthorn win sets up a qualifying final against the Swans at ANZ Stadium. A Hawks loss will see GWS travel to take on Geelong in a qualifying final.
NORTH MELBOURNE 3.1 5.3 6.8 9.9 (63)
GREATER WESTERN SYDNEY 2.5 6.8 10.11 14.16 (100)
GOALS
North Melbourne: Brown 3, Harvey 2, Ziebell, McDonald, Daw, Cunnington
Greater Western Sydney: Patton 5, Johnson 4, Smith 2, Cameron, Hopper, Ward
BEST
North Melbourne: Harvey, Brown, Ziebell, Mullett, Gibson
Greater Western Sydney: Patton, Johnson, Smith, Shiel, Scully, Shaw
INJURIES
North Melbourne: Macmillan (hip)
Greater Western Sydney: Whitfield (ribs)
Reports: Nil
Umpires: Donlon, Schmitt, Meredith
Official crowd: 22,295 at Etihad Stadium
