The women's football tournament will start the sporting action at this year's Olympic Games tomorrow, days before the Opening Ceremony.
There are due to be six matches take place and among those to feature will be hosts Brazil and the defending champions the United States.
Brazil will be in action against China at the Estádio Olímpico João Havelange in Rio de Janeiro at 4pm.
Local hopes will be pinned on Marta, a five-times Women's World Player of the Year, but who has never won an Olympic gold medal.
She was in the Brazilian team that lost the Olympic finals to the US at Athens 2004 and Beijing 2008.
Brazil will be feeling confident following their 3-1 win over Australia in a warm-up match in front of over 10,000 fans in Fortaleza.
China, now under the leadership of former France head coach Bruno Bini, have been getting plenty of practice minutes in before their Rio 2016 opener - losing 1-0 to France and Canada and defeating Zimbabwe 3-0 - and are aiming to get to the podium themselves.
Brazil be motivated by playing in front of their country at home on the world’s stage but also by their poor performance at last year's FIFA World Cup, where they were knocked out in the last 16 by Australia.
That tournament was won by the US, whose victory was their third in the tournament, making them the event's most successful team.
They have also won four of the five Olympic gold medals since the sport made its women's debut at Atlanta 1996.
The only time the US missed out on the gold medal was at Sydney 2000 when Norway won the final 3-2 thanks to a golden goal.
The US are scheduled to start their Group G campaign against New Zealand, who are ranked 17th in the world at Mineirao in Belo Horizonte at 7pm.
Brazil's coach Oswaldo Alvarez has brought in a psychologist to help them prepare for Rio 2016.
"All the eyes will be on us and on women's football," he said.
"But we know we are well prepared.
"We just want to play and win. In relation to emotional control, we will have to live with that.
"The Brazil women's football team plays very little at home.
"Now we will have the supporters with us, but at the same time they will ask for more.
"We already talked about that. We have a psychologist, we are working with him."
If the US do hold off the Brazilian challenge, they will become the first team of either gender to add an Olympic Games gold medal to a World Cup title back-to-back.
Considering they have lost just once in their last 41 games, it would take a brave person to bet against them.
Boosting their chances is fact that Japan, the country they beat at London 2012 and in last year's FIFA World Cup final, have failed to qualify.
“I don’t think anything compares to the expectations we have for one another," said Becky Sauerbrunn, co-captain of the American team, told US Soccer.
"We know how difficult it will be to be back-to-back winners.
"That pressure drives us.
"We always look for that next challenge because we constantly want to achieve that next level of greatness."
The competition has been split into three groups, with the group winners and runners-up progressing to the the quarter-finals along with the best two third placed teams.
The gold medal match is due to take place on August 20 at the Maracanã stadium.
Unlike the men's tournament, which requires teams to field under-23 squads with three exempt players, women's Olympic soccer has no such limitations bringing together the best players in the world.
The tournament will be played in seven venues across Brazil, including the jungle city of Manaus, in the Amazon rain forest.
The first match will be in Group E and features Sweden against South Africa at the Estádio Olímpico João Havelange at 1pm.
That is due to be followed at 2pm by Australia meeting Canada at the Corinthians Arena in São Paulo.
Other matches on the opening day will be Zimbabwe, making their first appearance in a major tournament and ranked 93rd in the world, against two-time Olympic bronze medallists Germany in São Paulo and France versus Colombia in Belo Horizonte.