Brazil will play Germany in the Women's World Cup final after beating USA 4-0 in a controversial last four encounter.

Leslie Osborne headed an own-goal before two goals from the superb Marta and one from Christiane saw the world's top-ranked team humbled.

Although the final scoreline was emphatic, the result hinged on two key decisions - one by US coach Greg Ryan, the other by referee Nicole Petignat.

The Swiss official sent off midfielder Shannon Boxx in farcical circumstances late in the first half, in an incident that will do little to lend the women's game credibility.

Ryan made the surprising move of changing his goalkeeper, selecting Briana Scurry ahead of Hope Solo despite the latter's impeccable track record.

Scurry was picked on the strength of her allegedly superior reactions, but proved deficient in every other department as the dejected Solo was forced to look on from the bench.

The goalkeeper was involved in a communication breakdown on 20 minutes that resulted in Osborne glancing a header into her own net under no pressure to give Brazil a lead they scarcely deserved.

Seven minutes later the 36-year-old was at fault again, letting a weak Marta shot from the edge of the box slip through her grasp as the underdogs moved further ahead.

Still the USA looked capable of mounting a comeback with bruising centre-forward Abby Wambach and Kristine Lilly both threatening.

But American hopes were all but extinguished by Petignat when Boxx, who had already been booked, was accidentally tripped from behind by Christiane as they tangled legs.

Bizarrely, the official decided Boxx was at fault and brandished the disbelieving midfielder a second yellow card.

It was as inexcusable as refereeing decisions get - if Petignat didn't see the incident, why guess Boxx was at fault, particularly when she had already been booked?

Thereafter it was all Brazil. A slick passing move led to a third goal on 56 minutes as Christiane's left-foot shot gave Scurry no chance.

Marta added more gloss to the scoreline late on, as she flicked the ball past her marker with an outrageous piece of skill, and again her shot had just enough power to beat the hapless Scurry.

Christiane struck the post again as Team USA and the Brazilians unleashed their full array of tricks - Marta showing just why she had been dubbed a female equivalent to Ronaldinho.

The defending champions await in Sunday's final, while Solo can expect to return for the USA in time for the third-place play-off against Norway.

Alex Chick / Eurosport