Western Australia 1 for 67 (Whiteman 37*, Freeman 1-10) trail Tasmania 179 (Ward 44, Rocchiccioli 4-31, Stobo 3-28) by 112 runs
Offspinner Corey Rocchiccioli claimed four wickets on the pace-friendly WACA surface as defending Sheffield Shield champions Western Australia continued their stranglehold over Tasmania after a dominant day one performance.
Rocchiccioli equalled his best first-class figures of 4 for 31 to tear through Tasmania, who were bowled out for 179 after winning the toss.
In reply, WA were 1 for 67 at stumps as they eye victory to secure a home final for the second straight year.
Opener Cameron Bancroft, the leading Shield run-scorer this season, looked in superb touch before prodding offspinner Jarrod Freeman to short-leg on 28.
With rain falling, a rarity in Perth this time of year, there was a 20-minute delay late in the final session but Sam Whiteman refocused on resumption alongside nightwatchman Rocchiccioli to complete WA's strong opening day.
With their hopes of qualifying for the final in the balance, Tasmania were desperate to make amends after copping a 383-run thrashing to WA at home last week.
Skipper Jordan Silk elected to bowl in humid and overcast conditions. It seemed a risk on a green-tinged surface and with seam bowling dominating the bat in the matches at the ground earlier in the season.
But in the first Shield match at the WACA in almost three months, the surface appeared benign with Tasmania openers Tim Ward and Caleb Jewell relatively untroubled in a 72-run partnership.
They almost batted through the opening session until Jewell fell just before lunch for 40 after being brilliantly caught by Mitchell Marsh at slip off the bowling of Rocchiccioli.
No.3 Jake Doran had a reprieve moments later when he was dropped by Bancroft at slip as Tasmania reached lunch at 1 for 80.
Having bowled within themselves in the first session, WA's attack was ignited by a stunning one-handed return catch low to the ground from quick Charlie Stobo to remove Ward for 44.
It triggered a collapse for Tasmania, who lost 3 for 11 with Doran and Mac Wright falling to brilliant line and length bowling from Stobo and Matt Kelly.
But Silk and Tim Paine steadied the ship with a fighting partnership to thwart a WA attack intent on opening up the lower order.
Marsh, who impressed with his rotation of bowlers, pulled a masterstroke by reverting back to under-used Rocchiccioli just before tea. Once again, the offspinner snared a wicket before a break when he removed Silk for 18.
As the threat of a thunderstorm loomed, Tasmania's lower order were blown away after Paine holed out for 17. They lost their last six wickets for 30 to ensure Tasmania failed to reach 200 runs for the third straight innings against WA.
Rocchiccioli finished with the spoils having retained his spot in the side as spinning allrounder Ashton Agar, who was sent home from Australia's tour of India after being overlooked for selection, focuses on white-ball cricket.
Agar is set to play in the 50-over Marsh Cup final between WA and South Australia on March 8 before returning to India for the ODI leg of the tour.
Marsh, meanwhile, stepped up his preparation for the ODI series having recently returned from a three-month injury layoff. The allrounder will play as a specialist batter in his first Shield match in two years.
Tasmania dropped wicketkeeper-batter Ben McDermott, a former Australia ODI and T20I player who has struggled this domestic season, while veteran seamer Peter Siddle was rested.
