Lancaster looks destined to clinch sixth spot after a percentage boosting win against Ardmona on Saturday, shutting the door on Undera (seventh) and Merrigum (eighth).
The Wombats - led by a 12-goal haul from sharpshooter Billy Ryan - breezed past the Bush Cats to record a 52.32 (344) to 2.1 (13) win.
The win at Lancaster Recreation Reserve rocketed the Wombats' percentage to 217 with one round remaining.
For Undera to sneak in and dislodge Lancaster from sixth, the Wombats would need to suffer a 200-point loss to Tallygaroopna, who is coming off its first loss since the 2017 elimination final, on Saturday.
Leading the way for Lancaster was Jack Donnell (three goals), Besim Besim (two), Zach Cerrone (seven) and Zaid Besim (seven).
Ardmona's Caine Atkinson, Charles Jackson and Isaac Handy were strong performers, while Tim Keegan booted two goals.
Elsewhere, Murchison-Toolamba ended Merrigum's dreams of finals football, running out 12.12 (84) to 8.11 (59) winners.
Brayden Cecchin led the way for the Grasshoppers, alongside James Londrigan and Ashton Cashion.
Jake Ross and Jack Sinclair were the Bulldogs' better players.
At Central Park Reserve, Undera was too strong for a young Shepparton East outfit, as the Lions cruised to a 18.18 (126) to 7.5 (47) win.
Undera's star forward Brenton Campbell booted eight majors - finishing his season tally on 52 from eight games.
Gun midfielder Kaine Herbert and Mitch Kyle were named Undera's best, while Shepparton East's Jayden Damianopoulos, Josh Brown and Jeromy Aynsley stood tall for the Eagles.
Meanwhile, Rushworth's Isaiah Johnson continued his blistering form, booting nine goals in a 22.18 (150) to 4.6 (30) rout of Longwood.
Joseph Thomson pipped Johnson for best afield honours, while Longwood's Michael Lane and Lachlan Cox (two goals) fought bravely.
Lastly, Avenel clinched its 11th straight win, defeating Dookie United 21.5 (131) to 8.11 (59).
Swans playing coach Kasey Duncan shone brightly in his return to the side - kicking 10 majors - while Lachlan Watts and Michael Berry chipped in with superb efforts.
For United, Riley Hamilton performed at his best and teammate Nick Geddes stood tall with four majors.
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