Australia beat a tenacious South Africa by four wickets to secure a place in the ICC Under-19 World Cup final on Monday.
Australia captain Will Bosisto won an important toss and elected to bowl in overcast conditions, at the Tony Ireland stadium, in Townsville.
West Australia's Joel Paris and Queensland's Mark Steketee both struck early with the new ball, dismissing South African danger men Quentin de Kock (1) and Gihahn Cloete (0).
Steketee returned for his second spell and took the crucial wicket of South Africa captain Chad Bowes (46), who had struck up a handy partnership of 88 with Murray Coetzee.
Coetzee went on to score 50 before he was run-out by a direct hit from West Australia's Ashton Turner.
New South Wales's Gurinder Sandhu bowled great line and length in the morning, ending with the tidy figures of 10-3-23-2.
In reply, Australia lost the early wickets of Queensland's James Peirson and Victoria's Meyrick Buchanan.
Opening batsman Cameron Bancroft of West Australia and New South Wales's Kurtis Patterson both soaked up the occasion and combined for a crucial partnership of 95 before Patterson was caught behind by de Kock.
Bosisto once again showed his class at the crease as he and Bancroft chipped away for a fourth wicket stand of 75 before Bancroft was run-out for 66.
Bosisto looked likely to take Australia through to the win before he was run-out by Theunis de Bruyn for 40, his first dismissal for the tournament, when Australia were three runs short of the target of 192.
Turner kept his head under pressure and hit a four to extra cover to seal victory for the young Australians with nine balls to spare.
Man of the Match Bancroft said: "I think it was a tough wicket to score off; it was one of those wickets where you had to bat for a long period of time.
"If you set yourself in those first nine overs early on it makes things a lot easier later on," he said.
"I am really proud of myself; it would have been nice to be not out at the end, but it doesn't always happen and I am just rapt that we are going to be playing on Sunday."
Bancroft said it was difficult to face the new ball at this ground.
"You saw South Africa lose early wickets and we lost early wickets as well. It is one of those wickets where you have to guts it out for the first twelve and after that scoring is always going to be a lot easier," he added.
Australia will play the winner of the second semi-final, between India and New Zealand, on Sunday at Tony Ireland Stadium.