Played in wet conditions at Bendigo's Queen Elizabeth Oval, the Bushrangers were left to rue inaccuracy in front of goals as the Rebels clinched a 15-point victory.
The round 17 loss comes one week before Sunday's wildcard match against the Dandenong Stingrays at Box Hill Oval - with the victor winning through to play finals.
Coach Mark Brown said his side failed to adapt to the poor conditions that impacted the game.
"Prior to Sunday we have played well in those conditions, so going in we weren't too worried about the weather," Brown said.
"We just overused the ball and we weren't as clean as we would have liked."
The Rebels started the match perfectly, as their clean ball use gave them a two-point lead at the first break.
Murray was able to respond in the second term, dominating the possession and the inside 50 count.
However, the Bushrangers were unable to capitalise on their 34-18 forward 50 entries as the Rebels extended the margin to three points.
After losing the lead in the third term, Greater Western went on to boot five of the next seven goals of the match to record an 8.11 (59) to 5.14 (44) win.
"They controlled the game, almost from the get-go," Brown said.
"We were slow to start, not playing in three weeks didn't help us.
"We could never get the game on our terms.
"But it's not panic stations, we know what we need to address isn't anything major."
Tungamah's Nick Irvine (three marks, 12 disposals) played a starring role across half-back, while Seymour's Sam Durham (18 touches) and Shepparton United's Liam Fiore (three rebound 50s) stood tall.
United's Jye Chalcraft (22 disposals, four inside 50s) tried his hardest, while Euroa's Tom Panuccio, Congupna's Jimmy Boyer and Jye's younger brother, Kade, all kicked one major each.
Brown praised the performance of Irvine and his ability to win one-on-one contests in defence.
"Nick played a superb game across half-back, he barely lost a one-on-one contest," he said.
"He's really strong in that area (one-on-one), fingers crossed his form continues because he's had a tough run this year."
The wildcard round match against Dandenong will start at 2.15pm on Sunday at Box Hill City Oval.
THE GAME
Murray Bushrangers 1.1, 2.7, 3.9, 5.14 (44)
Greater Western Rebels 1.3, 3.4, 6.9, 8.11 (59)
Bushies goals: Ben Kelly, Kade Chalcraft, James Boyer, Tom Panuccio, Dom Bedendo.
Bushies best: Nick Irvine, Sam Durham, Liam Fiore, Jye Chalcraft, Cam McLeod, Ben Kelly.
6°C