Western United are the first team into the Far West football grand final following a 97-point demolition of Koonibba on Saturday.
Dominant displays in the second and third quarters helped the Penong side to a 20-8 (128) to 4-7 (31) victory.
Jarrad Kenchington and Jarden Stoetzer led the way with five goals each for the Tigers, while Jesse Chandler struck four times.
Lawrence Benbolt, who kicked two goals, got the scoring underway for the Roosters, only for Western United to grab the next three goals which helped them to a 16-point advantage at the first break.
The Tigers extended the lead to 42 points after taking control of the second term with five goals to one.
Koonibba looked fired up as they chased a third-quarter revival only to be tormented by the Tigers, who piled on eight goals to two behinds to make the result safe.
Ahead by 89 points, Western United eased off in the final term yet still managed to kick three goals to a lone Koonibba major to book a spot in the decider in a fortnight.
The Roosters will aim to bounce back when they face the Blues in this weekend’s preliminary final.
Western United also progressed to the B grade grand final with a tense nine-point triumph versus Koonibba.
A pivotal third quarter performance saw the Tigers pull clear as they held on to win 10-7 (67) to 8-10 (58).
The Roosters led by two points at quarter-time, with that margin maintained following three goals apiece in the second quarter.
Western United pulled clear in the third term as they bagged five goals to one which took them 23 points clear.
The Tigers could only muster one goal in the final term as Koonibba came home strong with three majors which threatened to see them overturn the deficit.
Western United’s Lyndon Brown, John Polkinghorne and Edwin Gray were the only players to kick more than one goal in the match.
Koonibba will meet the Blues this weekend with a spot in the grand final on the line.
Thevenard reached the under 17 grand final with a 5-9 (39) to 3-9 (27) win over Western United.
Lachlan Wilkins proved vital with three goals for the Magpies which helped them to 12-point triumph.
Just six points separated the teams at both quarter-time and the main break, with Thevenard then kicking two goals to one in the third term to extend their lead to 11 points.
That would be enough as neither side could get one through the middle in the final term, in difficult conditions.
The Magpies will face either Koonibba or Western United in the grand final.
Western United defeated Koonibba in the under 14 clash by seven points.
The Tigers did just enough to keep ahead as it finished 3-7 (25) to 3-0 (18).
They await the winner of the Blues and Koonibba in the grand final.