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The U.S. women's national soccer team has maintained its status as the best in the world without winning a Women's World Cup in over a decade for one reason: Olympic dominance.

The United States has not won the Women's World Cup since 1999, a title sealed by the memorable penalty kick and celebration from Brandi Chastain that clinched the shootout win over China at the Rose Bowl.

The Americans finished third in the 2003 and 2007 World Cups, and were runner- up in 2011 to Japan. But in addition to earning gold in the 1996 Olympics, the United States won the Olympics in 2004 and 2008. It earned silver in 2000.

On the strength of those wins, the United States has held onto its spot as the best, although opponents have closed what was once a noticeable gap.

After failing to win the last two World Cups, the United States responded with Olympic gold. U.S. coach Pia Sundhage is confident of another golden response this summer.

"We are full of confidence and we'll have fun at the Olympics," Sundhage said. "We are ready."

Sundhage has assembled a team of 18 players, 17 who were on last year's World Cup team, led by the dynamic attacking duo of veteran Abby Wambach and rising star Alex Morgan.

The 32-year-old Wambach has 138 goals in 182 matches, and Morgan has 27 in 42 games for the United States. Coupled with six other players with at least 100 caps, including captain Christie Rampone and her incredible 260, there is good reason for optimism in the London Games.

And if the Americans needed a confidence boost ahead of the Olympics, they got it last month with a 4-1 win over Japan. The Japanese did defeat the Americans earlier this year, and the teams also tied another meeting.

"I think we needed that win against Japan for our confidence," U.S. midfielder Lauren Cheney said.

"Anytime you can beat one of the best teams in the world, it feels good," said Wambach. "But this is only the beginning. We know we can play even better."

Canada will enter the Olympics full of confidence as well.

Although Canada is not expected to be a threat for gold, they played very well in a 2-1 loss to the United States in late June. The game proved to coach John Herdman the Canadians are capable of being a surprise team.

"We were one goal away from the potential gold medallists," Herdman said. "Our progress has been quite solid. I'm quite happy."

Canada placed eighth in 2008 and, with star and captain Christine Sinclair and her 135 goals in 182 career appearances still with the squad, this summer will be a chance for the 2015 Women's World Cup hosts to make a lasting impression.

The United States is in Group G with Colombia, France and North Korea. Canada is in Group G with Japan, South Africa and Sweden. Group E has Brazil, Great Britain, Cameroon and New Zealand.

The tournament starts July 25, and the top two teams from each group, as well as the two best third-place finishers, advance to the quarterfinals. The gold medal match will be Aug. 9.

GROUP E

Two-time defending Olympic silver medalist Brazil is the class of this group. In addition to silvers in 2003 and 2007, the Brazilians finished second in the 2007 Women's World Cup. Five-time world player of the Year Marta, who is still just 26, remains the star of the team. With a solid defensive effort, this may be the summer Brazil breaks through. Great Britain should finish behind Brazil with a squad full of England players, while Cameroon and New Zealand will try to reach the quarterfinals as the third-place team.

GROUP F

World Cup champion Japan is the team to beat in a tough group, but no side has ever won the World Cup-Olympics double. The Japanese, guided by reigning FIFA world player of the year Homare Sawa, are capable of becoming the first. Japan still does not get enough respect after its WWC triumph. Canada showed the gap is closing as it tries to attain elite status, but it needs a great tournament to prove it on a big stage. Sweden was third in the WWC last year, and remains a dangerous team. South Africa is not expected to do much this summer.

GROUP G

The United States will not have an easy time in a group with solid squads such as France and North Korea, but this stage should prove to be nothing more than a bump in the road. France finished fourth at the Women's World Cup last year, and North Korea has qualified for the last four World Cups, so both could make the quarterfinals. Colombia is the weakest squad in the group, but the country made last year's World Cup and has some solid young talent. Right now, though, the South American country is not ready to take the next step.

On the men's side, two-time defending champion Argentina will not be back to go for a third straight gold medal, leaving much of the focus centered on whether or not Brazil can finally claim that elusive Olympic gold.

For a nation that has accomplished just about everything in the sport, an Olympic gold medal in men's soccer is one of the last things missing from Brazil's trophy cabinet.

And it is something that a loaded Brazil team will try to fix in London this summer.

Coach Mano Menezes has a talented group of young players at his disposal, with much of the attention being grabbed by 20-year-old striker Neymar.

The Santos forward is one of the most exciting young talents in the world and he can take another step toward superstardom by helping his nation capture Olympic gold.

"We've got everything we need to be champions," Neymar told fifa.com. "I think Brazil are always one of the favorites, no matter what the competition. It's always been that way."

Along with Brazil, Spain must also be considered a serious threat for gold with a team that could include Euro 2012 champions Jordi Alba, Juan Mata and Javi Martinez, along with Atletico Madrid striker Adrian Lopez, who won the Golden Boot as Spain captured the Under-21 European Championship last summer.

Great Britain will be competing in the men's Olympic tournament for the first time in 52 years, and the hosts should have a chance to medal with a side that will be captained by Manchester United veteran Ryan Giggs.

GROUP A

After winning gold at the 1908 and 1912 Olympics, Great Britain's history in the competition is limited, and the team will appear in its first Olympic tournament since 1960. As hosts, Team GB will be expected to make a run at a medal, and along with Giggs, a group of good young players will give the side a chance. England's Under-21 team failed to win a game at the European Championships last summer, but players like Ryan Bertrand, Jack Rodwell, Marc Albrighton and Jordan Henderson give coach Stuart Pearce plenty of options. If there is one side that will push Great Britain in this group it is Uruguay, which is returning to the Olympics for the first time since 1928. The nation has returned to the top level in the sport having finished fourth at the 2010 World Cup, won the 2011 Copa America and reached the final of the Under-17 World Cup. Uruguay figures to be strong in attack with world-class forwards Luis Suarez and Edinson Cavani being included as overage players. The other two teams in the group, Senegal and United Arab Emirates, are playing in their first Olympics.

GROUP B

This is the most wide open group in the field with Mexico entering as favorites but needing to overcome good teams from both Korea Republic and Switzerland. The Mexicans best finish at the Olympics was fourth place in 1968, but the team will be gunning for a medal in London with a side that includes Alan Pulido and Marco Fabian, who scored five goals apiece to lead Mexico in qualifying. El Tri will also be attempting to build on its recent success at the youth levels having won the Under-17 World Cup in 2011 and finishing third at the Under-20 World Cup. Mexico won all five of its qualifying matches by a combined score of 26-3. Korea Republic failed to advance past the group stage at the 2008 Olympics, but the Under-23 team is currently riding a 14-game unbeaten streak. Switzerland also figures to be in the mix to advance from the group as the Swiss reached the final of the Under-21 European Championship before losing to Spain. Gabon will be the fourth team in the group and it will be the first appearance at the Olympics for the African nation.

GROUP C

Brazil will be a huge favorite to win Group C, and after winning silver medals in 1984 and 1988, will be expected to make a serious run at gold. The Brazilian roster includes some of the better young players in the world with Neymar, Paulo Henrique Ganso, Lucas and Leandro Damiao, while overage players Hulk, Thiago Silva and Marcelo will bring experience to the team. Brazil will be one of the most exciting sides to watch in London, and if there is one team in the group that will give it even a bit of a test it will be Egypt. The Egyptians have taken part in 10 Olympic tournaments, with fourth-place finishes in 1928 and 1968. There is talent on the team but a propensity to underachieve in big spots must be overcome. Qualifying for this summer's competition has to represent the biggest success in soccer for Belarus, which hadn't qualified for a major tournament since gaining independence in 1991. Along with Belarus, New Zealand will try to pull an upset and reach the knockout round after qualifying for its second Olympic competition. The Kiwis first participated in men's Olympic soccer in 2008, where they managed to score one goal and pick up one point in three games.

GROUP D

Spain is the class of this group and is one of the favorites to win the tournament, which would only add to the incredible success that La Roja has enjoyed in recent years. The national team has gained all of the attention after winning Euro 2008, the 2010 World Cup, and then defending its Euro title this past summer. This is indeed a dominant era for Spanish soccer, but one that could continue with a strong side in London. Spain's last Olympic appearance came in 2000, and resulted in a silver medal. But with players like Alba, Martinez, Lopez and Mata as well as Athletic Bilbao duo Iker Muniain and Ander Herrera, there is more than enough ability on this team for more honors to be headed back to Spain. Japan will hope to test Spain in Group D as the Japanese will be playing in the Olympic tournament for the fourth straight time. Japan enters London in good form having lost just one of its eight games in qualifying. Honduras has reached the competition for the third time, but has yet to advance beyond the group stage, while Morocco is at the Olympics for the seventh time, but is still searching for its first medal.