A study by workplace health consultant Direct Health has estimated that up to 25 percent of the workforce could stay home to sleep off hangovers after the game, costing the economy over A$250 million ($185 million).

Soccer fever has gripped sports-mad Australia with an estimated 7 million people tuning in to see the "Socceroos" come from behind to beat Japan 3-1 in their opening match in Germany on Monday, setting a record for late night viewing.

Australia's first victory in a World Cup finals match after reaching the game's showpiece event for the first time since 1974 caused thousands of fans to turn up late for work following celebrations in the streets into the early hours.

Win or lose against soccer giants Brazil, employers are again likely to look out on a few empty seats on Monday morning, but politicians, always with an ear to the popular mood, have called on them to show understanding.

Federal Opposition Leader Kim Beazley echoed former Prime Minister Bob Hawke's famous line defending sports fans.

"Any boss who sacks his worker today is a bum. That's what Bob said," Beazley said in an interview with the Ten Network.

"These things happen very rarely. I am sure that they will take a very generous view of the outcome tomorrow," he said.

New South Wales state premier Morris Iemma also urged a lenient approach.

"Monday morning might get off to a slow start in New South Wales," he told Reuters.

"But bosses should go easy on staff turning up late for work that day. They will have been up all night wanting to be part of the nation's sporting history."

The Brazil game kicks off at 2 a.m. (1600 GMT Sunday) in Australia's big east coast cities of Sydney, Melbourne and Brisbane.

($1=A$1.35)