London Olympics | Relay races

Carmelita Jeter crosses the finish line as anchor of the U.S. 4x100 relay team after it sets a world record of 40.82 seconds. (Wally Skalij / Los Angeles Times)

Aug. 10, 2012 6:05 PM PT

The United States’ 4x100 women’s relay team sets a world record on its way to gold. The U.S. men’s 4x400 relay team loses to the Bahamas.

Members of the U.S. women’s 4x100-meter relay team -- Tianna Madison, Allyson Felix, Bianca Knight and Carmelita Jeter -- celebrate their world record mark. (Morry Gash / Associated Press)

Carmelita Jeter of the United States takes the baton from Bianca Knight on the last leg of the 4x100 relay race. (Wally Skalij / Los Angeles Times)

Allyson Felix passes the baton to U.S. teammate Bianca Knight. (Bernd Thissen / EPA)

United States’ Carmelita Jeter points to the time clock after crossing the finish line. The United States relay team set a world record with a time of 40.82 seconds (Martin Meissner / Associated Press)

Keisha Baker of the United States, right, collides with Brazil’s Jailma de Lima during the 4x400 preliminary. (Wally Skalij / Los Angeles Times)

Bahamas’ 4x400-meter relay team of Chris Brown, Demetrius Pinder, Michael Mathieu and Ramon Miller celebrate their victory and gold medal. (Martin Meissner / Associated Press)