Sri Lanka captain Mahela Jayawardene expected Australia to set a target of around 230 before they were routed for just 74 on Friday.
Australia won the toss and elected to bat in the third one-day international at the Gabba before Sri Lanka's Nulan Kulasekara tore through the order taking 5-22.
The score was Australia's third lowest in one-day history, narrowly surpassing two totals of 70 made against New Zealand in Adelaide in 1986 and England in Birmingham in 1977.
Sri Lanka chased down the target in 20 overs for a four-wicket win and a 2-1 lead in the five-match series.
"We were thinking 220 or 230 might be a par score and under lights you can probably chase something under 250," Jayawardene said.
"That was our target but it's a funny game.
"When you create opportunities and build pressure then anything can happen so a lot of credit to the bowling unit - they bowled really well.
"I know we lost a few wickets but it's always tough when you're chasing a small target in Australia - you don't know whether to go hard or not.
"But we got there and we're 2-1 up in the series so we're pretty happy."
Kulasekara was named man of the match, while fellow paceman Lasith Malinga added 3-14 as Australia struggled against the combination of swing and seam.
"I was telling the boys it might be a good track and that we could try and keep it to a decent score that we could chase down," Jayawardene said.
"Kula bowled in some really good areas, swung the ball and Lasith came and backed him up so I'm pretty pleased with the effort.
"If before the game started you'd have said we were going to win by four wickets, I'd have taken that."
The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of Cricket Australia
First Posted 19 January, 2013 9:37AM AEST