Australia's new-model Oarsome Foursome broke Great Britain's stranglehold of rowing's coxless four in Munich on Sunday night (AEST) to deliver a key psychological blow before the London Olympics.
Triple Olympic champion Drew Ginn's crew led Britain's priority boat all the way to triumph in World Cup 3 - the final preparation regatta ahead of the Games.
The Brits have dominated the event at the last three Olympics since Ginn debuted as a 21-year old alongside James Tomkins, Mike McKay and Nick Green and triumphed at the 1996 Atlanta Games.
But Australia's new four - also containing Josh Dunkley-Smith, James Chapman and Will Lockwood - had the world champions' measure throughout to win by half a length in six minutes 10.28 seconds.
The GB quartet were visibly pained by the 0.87sec defeat and Chapman expected the result to heap extra pressure on the gold-medal favourites five weeks before the London Games.
"It will hurt them like it would have hurt us if we didn't win," the Sydney oarsman told AAP.
"They're meant to be the No.1 British heavyweight sweep boat. They are a genuine gold opportunity for their medal tally in their home Olympics.
"There's some extra pressure of expectation of hosting the Olympic Games and this might start to create some doubts in their minds."
After leading the Brits for 1750m in World Cup 2 three weeks ago in Switzerland before being overrun, Chapman denied the Australians felt they had to lower their colours before London.
"Any opportunities you get to put a dent in your opposition's confidence is a good thing to do but it isn't necessary," he said.
"This is one of the lead-up events and it's not the real show so it indicates to us that our preparation is on track and we're moving in the right direction.
"They're good athletes and they'll come back swinging, no doubt."
The men's four gold was the highlight of an encouraging finals day in Munich for Australia which also featured four silver medals.
The women's double sculls crew of Kim Crow and Brooke Pratley, the men's pair of James Marburg and Brodie Buckland, the men's lightweight four and the men's eight all finished runners-up.
Crow and Pratley's effort, in their first international event together, is almost certain to see them selected together in the double in a blow to exiled sculler Pippa Savage's hopes of rowing in London.
Savage's previous crew, the quad sculls, finished fourth, more than five seconds off the pace of winners Ukraine but she is next to no chance of being recalled to that boat after clashing with crew-mates.
Australia's world champion quad sculls crew finished a disappointing fifth, the same result as the women's eight.