Melbourne has put itself in prime position to land a prized AFLW top-two spot after fighting out a 10-point win over the Kangaroos at Casey Fields.
In Saturday's other matches, the Adelaide Crows stayed on top of the ladder with a nine-point victory over Fremantle, and Geelong defeated Richmond by 23 points.
The Demons led almost all night and their disciplined defence withstood a barrage of pressure from the in-form Kangaroos to prevail 4.3 (27) to 2.5 (17).
Melbourne joins the Crows on 28 points, a win ahead of the Kangaroos and third-placed Fremantle, who the Demons play next week.
Karen Paxman was brilliant for the Demons, racking up 28 disposals and a goal, while Tayla Harris booted two goals and took a wonderful second-quarter mark.
Kangaroos ball magnet Ashleigh Riddell had 29 disposals and Jasmine Garner collected 19 and booted a goal.
The Kangaroos had an early injury scare when Emma King (ankle) hobbled off the ground, though the ruck later returned.
Melbourne's Kate Hore landed the first blow of the match, then Paxman added her side's second after Tahlia Randall gave away a costly 50-metre penalty.
The Kangaroos were ferocious with their pressure around the ball and it finally paid dividends early in the second term when Jasmine Garner snapped brilliantly from a stoppage to put them on the board.
The Demons settled when Aileen Gilroy gave away a 50-metre penalty after mistakenly throwing the ball to her teammate rather than Harris after a free kick.
The gun forward made the Kangaroos pay, steering the ball through the breeze.
Harris received a contentious free kick at the start of the third term and coolly kicked her second goal.
Neither team kicked a goal again until Kaitlyn Ashmore set the match alight midway through the final quarter when she ran onto Riddell's searching long kick, burned off Daisy Pearce and slotted a difficult goal.
But between their inefficiency and Melbourne's stern defence, the Kangaroos were unable to capitalise on their 14 final-quarter inside-50s to the Demons' solitary entry.
Crows edge Dockers
Two-time All-Australian Anne Hatchard produced a midfield masterclass as she inspired Adelaide to its win over Fremantle.
The Crows could not manage a goal in the third term of the match at Fremantle Oval, meaning they turned for home down by two points and kicking against the breeze.
But Hatchard produced a scintillating burst early in the final quarter, tallying nine possessions within the space of a few minutes to set up two quick goals for the Crows.
They proved to be the final goals of the match, with Adelaide prevailing 3.7 (25) to 2.4 (16).
The result boosted Adelaide's win-loss record to 7-1, while Fremantle is now 6-2.
Hatchard finished with 30 disposals and eight marks in a best-afield display, while Ebony Marinoff was also damaging with 30 possessions.
Teammate Danielle Ponter starred up forward with two goals from 20 disposals.
Stephanie Cain collected a team-high 22 possessions for Fremantle, with Airlie Runnalls tallying 20 disposals and a goal.
Dockers captain Hayley Miller was restricted to 10 possessions and a goal in a quiet display.
Both sides entered the match minus key players.
Adelaide was without superstar Erin Phillips (knee), while the Dockers were missing midfield gun Kiara Bowers (knee) and forward Roxy Roux (hamstring).
Cats fire against Tigers
Geelong capitalised on a dominant first half against Richmond to snare its second win of the season.
The Cats set up the 5.3 (33) to 1.4 (10) win at Punt Road Oval with a rampant second quarter, where they booted four unanswered goals, to leapfrog the Tigers into 10th on the ladder.
Amy McDonald (26 disposals, 10 clearances) and Rebecca Webster (20 touches and a goal) set the tone in midfield for the Cats, with Phoebe McWilliams booting two goals and providing a strong presence up forward.
Richmond star Monique Conti overcame a slow start to collect 23 disposals and was supported by Sarah Hosking (14 disposals, five tackles) and Meagan Kiely (13 tackles).
Geelong drew first blood early when McWilliams took a big pack mark and coolly converted.
The Cats continued to dominate the first half with their relentless pressure and hard running on the outside, while the Tigers let themselves down with their execution and decision-making going forward.
The visitors broke the match open early in the second quarter when Kate Darby, Webster, Madisen Maguire and McWilliams hit the scoreboard in quick succession.
The Tigers finally broke through late in the term, when Conti found Katie Brennan and the Richmond skipper coolly converted, booting a goal for a 14th consecutive match.
The Brennan major stemmed Richmond's bleeding and ensured the half-time deficit was just 22 points.
The Tigers came out of the main break with renewed intensity but both teams went goalless in a third quarter that had plenty of hustle but little end product.
Richmond's Kodi Jacques limped off with a lower-leg injury in the third term, while Richmond forward Tayla Stahl also cut a dejected figure late after having treatment on her knee.
The Tigers and Cats traded a sole behind each in the final term, while Geelong's Olivia Barber had to come off after hitting her head on the turf after a mark.
AAP/ABC