Jonah Placid scored two tries as Australia saw off Samoa 34-22 in an entertaining U20s World Championship opener.
The Queensland Reds full-back scored a try in each half, with Michael Gunn, Andrew Deegan and Andrew Kellaway also crossing for the Wallabies.
However scores from Trent Winterstein, Josh Dowsing and Jarrad Adams kept Samoa in touch all the way and set up a tense finish.
Australia looked comfortable early on thanks to an early Deegan penalty, followed by a try from a forward drive by Gunn pushing them into an 8-0 lead.
Josh Ioane got Samoa on the board with a penalty but Australia responded through Placid after a long period of pressure, Deegan converting on this occasion.
Leading 15-3, Australia looked comfortable, but they lost Lukan Lealaiauloto-Tui to a yellow card for a dangerous tackle, and in his absence Winterstein crossed for Samoa.
Australia were next on the board, taking advantage of a yellow card for Mike Tamoaieta to send Deegan over, but the Australian fly-half was off-target with the conversion.
Just after the hour Dowsing went over from a rolling maul but Australia hit straight back through Placid to make it 27-15.
However when Adams went over with nine minutes remaining it looked set to be a thrilling finish, only for Kellaway to finally seal the win for Australia late on.
Tries: Gunn, Placid 2, Deegan, Kellaway
Cons: Deegan 3
Yellow card: Lealaiauloto-Tui
Tries: Winterstein, Dowsing, Adams
Cons: Falanniko 2
Yellow card: Tamoaieta
Australia: 15 Jonah Placid, 14 Alex Newsome, 13 Campbell Magnay, 12 Sione Tuipolotu, 11 Andrew Kellaway (c), 10 Andrew Deegan, 9 James Tuttle, 8 Adam Korczyk, 7 Michael Gunn, 6 Lolo Fakaosilea, 5 Lukan Lealaiauloto-Tui, 4 Ned Hanigan, 3 Matt Sandell, 2 Connal McInerney, 1 Cameron Orr
Replacements: 16 Fereti Saaga, 17 Folau Faingaa, 18 Tyrell Lomax, 19 Riley Winter, 20 Sam Croke, 21 Harry Nucifora, 22 James Dalgleish, 23 James Dalgleish
Samoa: 15 Chase Tiatia, 14 Trent Winterstein, 13 Pepesana Patafilo, 12 Jonathan Faauli, 11 Ah-Mu Tuimalealiifano, 10 Josh Ioane, 9 Jonathan Taumateine, 8 Josh Dowsing, 7 Uini Fetalaiga, 6 Giovanni Kueffner-Mulitalo, 5 Ben Tuiomanufili, 4 Ezra Meleisea, 3 Mike Tamoaieta, 2 Elia Elia, 1 Junior Halafuka
Replacements: 16 Ieremia Mataena, 17 Jarred Adams, 18 Marco Fepulea, 19 Jordan Jackett, 20 Gordon Langkilde, 21 Melani Matavao, 22 Orbyn Leger, 23 Malu Falanniko