Beijing, China (Sports Network) - Track and field heads into the sixth day of competition Wednesday with three gold medals on the line.

The main attraction will be the men's 200 meters final as Jamaica's Usain Bolt, winner of the 100m in world record time Saturday, takes on a trio of Americans, including defending gold medalist Shawn Crawford. Walter Dix, bronze medalist in the 100 at these Games, and Wallace Spearmon will also run for the Stars and Stripes.

The U.S. will also try for a couple of medals in the women's 400 meter hurdles as Sheena Tosta and Tiffany Ross-Williams are in the final. Tosta leads the pack, having posted the fast time of the qualification rounds.

Also awarded on Wednesday will be a gold medal in the women's hammer throw. Cuba's Yipsi Moreno, silver medalist in Athens, is one the favorites to win gold along with Aksana Miankova of Belarus and Germany's Betty Heidler, the 2007 world champion.

The undefeated U.S. men's basketball team takes the court against Australia Wednesday in the quarterfinals of the 2008 Olympics. Team USA (5-0) defeated Australia, 87-76, in an exhibition contest on August 5 in Shanghai, China, but the Aussies played that game without center Andrew Bogut. Australia has appeared in a total of 11 Olympic men's basketball competitions, and has three times finished fourth (1988, 1996 and 2000). The United States is 5-0 in Olympic play against Australia, including an 89-79 victory in 2004. The Americans also picked up victories in 1964 (78-45), 1972 (81-55), 1988 (78-49) and 1996 (101-73). The United States has clearly been the most dominant team in men's action. It has won its five games by an average of more than 32 points. In other quarterfinal action, Spain (4-1) will face Croatia (3-2), Lithuania (4-1) will take on host China (2-3) and Argentina (4-1) battles Greece (3-2). The winner of the USA/Australia contest will face the victor between Argentina and Greece in the semis.

The United States softball team takes on Japan in the semifinals. Currently holding a 21-game Olympic winning streak that dates to Sydney in 2000, the Americans will be looking for their fourth consecutive gold medal in softball's last appearance in the Olympics until at least 2016. Australia and Canada play in the other semifinal match with the bronze medal game taking place later in the afternoon.

The quarterfinals of men's volleyball will be highlighted by a showdown between the U.S. and Serbia. The Americans were unbeaten in the preliminary round and are heavy favorites going into that encounter. Elsewhere, Bulgaria plays Russia, Italy tangles with Poland, and the surprise Chinese team goes against gold medal contender Brazil.

Already with a semifinal berth, the U.S. baseball team plays Japan on Wednesday to decide who gets third or fourth place. Runs are hard to come by against Japan, which has compiled a 1.59 ERA, with that pitching staff at the top of the table in these Games. Conversely, the U.S. leads the tournament with the highest batting average at .276.

A pair of medal events will be awarded in taekwondo on Wednesday, the first of four days of competition in the sport. The men will battle in the -58 kilogram category and the women will meet in the -49kg weight class. Reigning world champion Juan Antonio Ramos from Spain and Taiwan's Chu Mu-Yen, the defending Olympic gold medalist, are the favorites, but could actually meet in the semifinals. Yang Shu-Chun of Taiwan and China's Wu Jingyu are the top competitors in the women's field. Wu won a world championship in 2007 and Yang was third in that competition.

The wrestling competition continues Wednesday with athletes battling for medals in the 66 and 74 kilogram weight classes. Russia's Buvaysa Saytiev will aim for his third Olympic gold in the 74kg, as he tries to equal legendary Soviet wrestler Alexander Medved for the most gold medals in freestyle wrestling. Meanwhile, Turkey's Ramazan Sahin, the defending world champion, will try to add a gold medal to his collection in the 66kg.

Michael Phelps might have taken his last plunge, but the swimming program hasn't quite wrapped up yet at the Beijing Olympics. The men's and women's marathon swims are scheduled for this week, with the women taking to the water early Wednesday morning for the 10-kilometer race. Russia's Larisa Ilchenko is an overwhelming favorite to win after claiming five consecutive 5 km world championships and three straight 10 km races.

Wrestling medals will be awarded Wednesday in the men's 74 kg and 66 kg weight classes. Buvaysa Saytiev, looking for his third Olympic gold medal, will begin his title defense at the 74 kg weight. American Ben Askren is among the challengers. In the 66kg class, world champion Ramazan Sahin is among the medal hopefuls.

Medal races are set for Wednesday in the RS:X category for men and women. Julien Bontemps of France has the lead in the men's class, while Yin Jian of China is at the top of the board in the women's division.

The defending Olympic and world champion Russian pair of Anastasia Ermakova and Anastasia Davydova are poised for gold again in synchronized swimming. They had another solid performance Tuesday in by finishing first in the duet preliminary round of the duet fee routine. The Russian duo incorporated several powerful lifts in their routine and swam disciplined as a unit, scoring a 49.5 ahead of Wednesday's final.

BMX cycling makes its Olympics debut on Wednesday. Great Britain's Shanaze Reade is the favorite to win the gold medal. Women's seedings are Wednesday with the semifinals and final slated for Thursday.

Going into Wednesday, the United States holds a slim 79-76 lead over China in the overall medal count, but the Chinese easily have the most gold with 43, compared to 26 for the U.S. Russia is making a charge with 42 overall medals with Australia next at 35. Great Britain has 33 medals, and on Tuesday the country passed the all-time 200 gold medal mark, finishing the day with 201. The Brits collected four more gold on Tuesday, bringing their total to 16, their best performance ever outside their home country.