A great first half display from the Irish coming out of the blocks with three tries, scored by Brian Carney, Felix Jones and Paul Marshall left it 17-7 at the break.
As ever with sevens rugby, Australia responded well in the second half with the scoreline showing in their favour going into the final minutes, but with a come back of the tournament Ireland secured the win in dramatic fashion to leave it 24-21.
Ireland's Gary Brown just after the win: "I feel great. We started off the tournamnet with a big beating from Samoa so we really needed to start well against Australia today. It was a great win. I only had a bit to do coming on at the end with a few minutes to go but you still get tired in those two minutes.You never know with Sevens. You have just got to keep your composure, especially when you are in the lead. You have just got to get control of the ball and then keep it. It can be like a game of tennis, with the ball going back and forth, but we are just delighted that we kept our composure and sealed the win."
Ireland go on to play Portugal this afternoon.
Ireland Rugby World Cup Sevens Squad
Gary Brown Blackrock College - Leinster
Kieran Campbell Galwegians - Connacht Captain
Brian Carney Clonakilty - Munster
James Coughlan Dolphin - Munster
Conan Doyle Garryowen - Munster
Tom Gleeson Cork Constitution - Munster
Eoghan Grace Shannon - Munster
Felix Jones Old Belvedere - Leinster (Moving to Munster)
Paul Marshall Ballynahinch - Ulster
Daniel Riordan Buccaneers - Connacht
Kyle Tonetti Blackrock College - Leinster
Brian Tuohy Cornish Pirates
Ireland Sevens Management
Hugh McCaughey Manager
Jon Skurr Coach
Simon Harland Doctor
Fergal O'Callaghan Team Support
Ashley Blair Team Support
Vinny Hammond Team Support