The NSW Blues need a strong batting performance to be sure of a place in the Sheffield Shield final.
The second-placed Blues resume on Sunday at 1-6 needing another 397 runs on the last day of the match in Perth to join Victoria in the final at Alice Springs.
Nic Maddinson (4) chopped on after WA declared at 4-275 late on Saturday, bringing stumps.
The Sheffield Shield’s highest runs scorer, Ed Cowan, will join Dan Hughes, who is yet to score.
Cowan currently has 879 runs at 73.25 with three centuries and a highest score of 212.
Western Australia dominated day three of the match, with discarded one-Test all-rounder Hilton Cartwright making a career-best 170 not out. It left him second to Cowan on the Shield run-scoring table with 861 runs at 53.81.
Cartwright, who played a single Test against Pakistan earlier in the summer, struck five sixes, including one that landed on top of the players' pavilion.
Former Test paceman Trent Copeland (3-72) was the pick of the NSW attack, with off-spinner Will Somerville claiming the other wicket.
Resuming at 5-242, NSW was bowled out for 309, with only some lusty blows from No.11 Doug Bollinger (32 not out) seeing NSW passed the follow-on mark.
It was Bollinger’s second highest score in 14 years of first class cricket, virtually doubling his runs this season to 69 at the rather respectable average of 23. This contrasts with an overall first class batting average of 8.45.