Brazil go into the match as favourites after destroying Germany, who had not previously conceded a goal, 4-1 in their semi-final with sparkling displays from forward Cristiane and World Player of the Year Marta.

They also beat the United States 4-0 in their last competitive meeting, a semi-final at the 2007 World Cup.

But both Brazil and Marta have earned a reputation for failing at the crucial moment.

The South Americans lost 2-1 to a golden goal against the United States four years ago and were beaten 2-0 by Germany in last year's World Cup final, when Marta missed a penalty.

Brazil coach Jorge Barcellos warned his team about the euphoria that followed their semi-final.

We haven't won anything yet, he said. We are one game away from the gold medal and we can't repeat the mistakes we made in the first half against Germany. There were lapses in concentration that could be fatal.

The United States, under former Swedish player Pia Sundhage, have gained momentum during the Games after a shock opening match defeat to Norway.

We're pumped. Bring it on, said midfielder Heather O'Reilly.

We've played Brazil before and we know they're a pretty awesome team with a lot of great personalities. But this team player for player is unified and strong, and we're together.