U.S. maintains reign in 4x400 with gold

DAEGU, South Korea -- The United States won its fourth straight men's 4x400-meter relay at the world championships, finishing ahead of South Africa.

Greg Nixon started off the race and handed to Bershawn Jackson. Angelo Taylor ran the third leg and LaShawn Merritt crossed the finish line first in 2 minutes, 59.31 seconds to give the United States its ninth gold medal of the championships.

South Africa finished second for silver in 2:59.87. Although double-amputee sprinter Oscar Pistorius was left out of the lineup, he still will get a medal for running in the heats.

Jamaica took bronze in 3:00.10.