EXCITING top-five draft prospect Izak Rankine has booted three goals to power South Australia over the top of the Allies at GMHBA Stadium on Friday, ensuring the Croweaters remain undefeated going into the final round of the NAB AFL Under-18 Championships.

South Australia will face off against fellow unbeaten side Vic Metro for the Under-18 title at Etihad Stadium next Wednesday, after the Croweaters charged home to a 24-point victory against the Allies.

Rankine, an All Australian in his bottom-age year in 2017, booted two classy goals in the third term as South Australia kicked six goals to the Allies' one in the quarter, eventually claiming an 13.12 (90) to 9.12 (66) victory.

The West Adelaide product finished with 20 disposals and six inside 50s in his best game of the Championships, with possible No.1 draft pick Jack Lukosius also impressing in a role further up the ground.

Lukosius, who at 195cm has the ability to play as a key forward or key defender, spent the majority of his time on the wing, where he racked up 18 disposals and showed off his precision field kicking.

Luke Valente (28 disposals and six clearances) and Jackson Hately (21 disposals and eight tackles) were also among the best for South Australia.

South Australia had to dig deep for victory after it trailed by 13 points at half-time, with Sydney father-son prospect Nick Blakey difficult to contain in attack.

As the Allies' focal point up forward, Blakey pushed his name further up draft boards with back-to-back goals in the second term, with his courage in aerial contests coming to the fore on several occasions.

Blakey, the son of North Melbourne champion and current Swans assistant John, has nominated Sydney as his preferred club (as a member of the Swans academy) and the youngster is likely to command a bid inside the top-10 of this year's NAB AFL Draft.

Bailey Scott, the son of former Cats and Roos player Robert is eligible as a father-son prospect to both clubs, as well as to Gold Coast as a member of its academy, gathered a team-high 22 disposals through the midfield.

Chayce Jones (21 touches) and Connor McFayden (21) were also high possession winners for the Allies, while Jacob Koschitzche – the cousin of former St Kilda ruckman Justin – held up strongly in the back half.

SOUTH AUSTRALIA 1.1 4.6 10.10 13.12 (90)

ALLIES 3.6 6.7 7.8 9.12 (66)

Goals

South Australia: Rankine 3, Jarvis 2, Rozee, Chapman, Munn, Woodcock, Betterman, Frederick, Sampson, Lukosius

Allies: Blakey 2, Scott 2, Quint, McFayden, O'Neill, Budarick, Mansell

Best

South Australia: Valente, Hately, Betterman, Rankine, Lukosius, Frederick

Allies: Scott, McFayden, Blakey, Jones, O'Neill, Briggs