Natallia Dobrynska (R) of Ukraine, leads the field as she competes in her women's heptathlon 100m hurdles heat during the London 2012 Olympic Games at the Olympic Stadium August 3, 2012.
American Michael Phelps bids goodbye to Olympic competition as the focus switches from swimming to track and field Friday at the 2012 London Olympics.
Phelps will seek his third gold medal of the London Games when he swims in the 100-meter butterfly race. The field of competitors includes South African Chad le Clos, who upset Phelps in the 200-meter butterfly final.
A win Friday would also give Phelps his third consecutive gold medal in the event after victories in 2004 and 2008. He pulled off the feat Thursday in the 200-meter individual race, becoming the first swimmer in Olympic history to win the same event at three consecutive Games. Phelps is the most decorated Olympian in history with 20 total medals.
On the women's side, Britain's Rebecca Addington will try and boost the host nation's gold medal haul when she defends her title in the 800-meter freestyle, while teenaged American swimmer Missy Franklin will go for her third gold in the 200 meter backstroke, going against two-time winner Kirsty Coventry of Zimbabwe.
The track and field competition gets underway at Olympic Stadium with the women's 10,000-meters final, as world champion Vivian Cheruiyot of Kenya takes on defending Olympic champion Tirunesh Dibaba of Ethiopia. Meanwhile, Ukraine's Nataliya Dobrynska will begin defense of her 2008 championship in the heptathlon, against a lineup featuring world champion Tatyana Chernova of Russia and British hopeful Jessica Ennis.
The United States is leading China in the overall medal count, 37 to 34, and are tied in the gold medal category with 18. South Korea is a distant third in the overall medal count with 14.
Photo Gallery: Day 6 of Competition
Day 6 of Competition
1/11Tyler Clary of the U.S. celebrates winning the men's 200m backstroke final with an Olympic record.
Photos from the sixth day of the Olympic Games in London.
2/11Japan's Shiho Otsuka (L) challenges South Korea's Lee Seonok in their women's Group A hockey match.
Photos from the sixth day of the Olympic Games in London.
3/11U.S. gymnast Gabrielle Douglas performs on the balance beam during the artistic gymnastics women's individual all-around competition.
Photos from the sixth day of the Olympic Games in London.
4/11Michael Phelps, left, and Ryan Lochte, both from the U.S., start in the men's 200-meter individual medley swimming final.
Photos from the sixth day of the Olympic Games in London.
5/11Prince William and his wife Kate watch track cycling at the velodrome.
Photos from the sixth day of the Olympic Games in London.
6/11Greece's goalkeeper Filipos Karampetsos blocks the ball during the men's preliminary round Group A water polo match against Kazakhstan.
Photos from the sixth day of the Olympic Games in London.
7/11Spain's Pablo Herrera Allepuz misses the ball during a beach volleyball match against Japan.
Photos from the sixth day of the Olympic Games in London.
8/11U.S. gymnast Gabrielle Douglas after receiving her gold medal during the artistic gymnastics women's individual all-around competition.
Photos from the sixth day of the Olympic Games in London.
9/11Russian President Vladimir Putin congratulates Russia's Tagir Khaibulaev after he defeated Mongolia's Tuvshinbayar Naidan in their men's -100kg final judo match.
Photos from the sixth day of the Olympic Games in London.
10/11Germany's Dimitrij Ovtcharov serves to Taiwan's Chuang Chih-yuan in the men's singles bronze medal table tennis match.
Photos from the sixth day of the Olympic Games in London.
11/11Russian President Vladimir Putin, Britain's Prime Minister David Cameron and Foreign Secretary William Hague watch the women's -78kg final judo match between Kayla Harrison of the U.S. and Britain's Gemma Gibbons.
Photos from the sixth day of the Olympic Games in London.
The Voice of America provides news and information in more than 40 languages to an estimated weekly audience of over 326 million people. Stories with the VOA News byline are the work of multiple VOA journalists and may contain information from wire service reports.
