In the final season of U/17 competition, Sturt and North will battle for a place in the GF to play Port.
The prelim will be played next Sunday at Adelaide Oval at 9:15am, before the two league finals.
North withstood a spirited effort by Glenelg in the first semi, winning by 20 points after trailing by seven at three quarter time, to progress to the prelim. Meanwhile, Sturt suffered their second successive loss - following 19 consecutive victories during the minor round - after surrendering a 50-point lead to Port in the other semi to go down by four points. The Magpies kicked 10 last-quarter goals to book their place in the GF.