Holding a 61-run first-innings lead after making 255 in reply to WA's 194, Victoria delivered another blow just before stumps on day two on Friday.
Mitchell Perry trapped former Australia opener Cameron Bancroft on the final ball of the third over to leave WA reeling at 1-4.
Instead of Australia's white-ball star Mitch Marsh arriving at the crease, spinner Corey Rocchiccioli was sent in as a nightwatchman.
Rocchiccioli survived five overs with captain Sam Whiteman to get WA to stumps at 1-5, still trailing Victoria by 56 runs.
Whiteman made just two from 24 balls, but did his job by getting to the end of the day without falling to the charging Victorian attack.
On a tricky wicket, opener Blake Macdonald thrived for Victoria with 79, while Matt Short compiled 62.
Victoria took their time building a lead, going at a run-rate of just 2.68 and batting for 96 overs.
WA veteran Cameron Gannon bowled tirelessly, sending down 23 overs for figures of 5-47.
Rocchiccioli ended Victoria's innings with his second wicket, finishing with 2-61.
Despite struggling in the one-day cup and suffering a heavy loss to WA on Tuesday, Victoria have been dominating the Shield this season.
Another win here would take them into the Big Bash League break with five wins from six matches, putting them in the box seat to host this season's final.
WA are on the bottom of the Shield table, having secured just one win this campaign.
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