The Blues will contest the Far West football A grade grand final after holding on for a thrilling four-point win against Koonibba on Saturday.
The preliminary final went down to the wire as the Blues went goalless in the final term but recorded an 11-9 (75) to 10-11 (71) victory.
Thomas Clayton and Bayln Thompson kicked three apiece for the Blues, as did Koonibba player Brandon Willis.
The win continued a rich vein of form for the Blues and was their fifth from the past six matches.
They carried the momentum from the win over Thevenard into the first quarter, using the wind to their advantage to kick five goals to none for a 32-point lead.
Koonibba reduced the deficit with a four-goal second quarter, however two Blues' majors helped maintain a 16-point margin.
An exciting third term saw two Willis goals get the Roosters to within four points only for the Blues to hit back with four of the next five.
Leading by 25 points but going against the wind in the final term the Blues knew they had to be resolute.
The Roosters poured forward hunting a comeback and a second Cody Colbung goal brought them to within five points, but that elusive decisive major did not arrive.
The Blues will face Western United at the Far West Aboriginal Sporting Complex this Saturday.
Western United cruised to an 83-point B grade win against Thevenard.
Westies dominated throughout to win 15-10 (100) to 2-5 (17).
The Tigers had eight scoring shots to none in the first term yet kept the Magpies in the hunt with six behinds, before extending the lead to 21 points by half-time.
Western United charged away in the third term with nine goals to no score which ended the match as a contest.
Kayden Peters and John Polkinghorne led the way with four goals each.
The Tigers now face Koonibba in the decider.
Thevenard triumphed by a single point in the under 17 match with Western United.
The Magpies hit back after quarter-time and kicked the only goal of the fourth term to win 5-9 (39) to 5-8 (38).
Western United's 17-point lead at the first break was wiped out by a fine Magpies revival in the second, with the Tigers recovering in the third term of a see-sawing contest.
Down by seven points at three-quarter time, Clinton Ginger kicked the match-winning goal for Thevenard.
Thevenard advances to face Koonibba in the grand final.
Koonibba was strong for three quarters to win the under 14 preliminary final against Western United.
The Roosters won by 47 points as it ended 7-12 (54) to 1-1 (7).
Westies kicked their only goal in the first term, as the Roosters ran away with the match after a goalless opening quarter.
Koonibba now faces the Blues in the showpiece.