LONDON -- Manteo Mitchell felt the pop in his leg and knew it wasn't good. "It felt like somebody literally just snapped my leg in half," he said.
The American sprinter had half a lap to go in the first leg of the 4x400-meter relay preliminaries Thursday and a choice to make: keep running or stop and lose the race. To him, it was never much of a choice.
He finished the lap and limped to the side to watch the Americans finish the race and qualify easily for the final. A few hours later, doctors confirmed what he suspected: He had run the last 200 meters with a broken left fibula.
"I heard it and I felt it," Mitchell told The Associated Press. "But I figured it's what almost any person would've done in that situation."
Mitchell finished his heat in a more-than-respectable 46.1 seconds, and the United States tied the Bahamas in the second heat in 2 minutes, 58.87 seconds -- the fastest time ever run in the first round of the relay at the Olympics.
The 25-year-old sprinter from Cullowhee, N.C., said he was diagnosed with a complete break of the left fibula -- but it was not a compound fracture and the bone is expected to heal on its own in four to six weeks.
He knew what the stakes were when he lined up to run the first leg of his first Olympics. The Americans have won gold in the last eight long relays they've entered at the Olympics.
"Even though track is an individual sport, you've got three guys depending on
Men's decathlon: World record-holder Ashton Eaton won the Olympic decathlon gold medal by 198 points.
Eaton set the decathlon world record at the U.S. trials in June and backed it up with an Olympic victory with 8,869 points.
Two-time world champion Trey Hardee of the U.S. settled for silver with 8,671 points, and Leonel Suarez of Cuba took the bronze, 346 points behind Eaton, at 8,523.
Eaton had a 151-point lead going into the final event, the 1,500 meters, and is a better middle-distance runner than Hardee. But there were still some nerves in the field, with a rare false start in the 1,500.
Eaton needed to slash six seconds off his fastest ever time in the 1,500 to break his world record but ran a cautious race and finished well outside his personal best in 4 minutes, 33.59 seconds.
Men's 800 meters: David Rudisha won his first Olympic gold medal with the kind of world-record performance that has made him almost unbeatable the last three years. The 23-year-old Kenyan won the final in 1 minute, 40.91 seconds, shaving one-tenth of a second off the mark he set in 2010, and setting the first world record on the track at the London Olympics. Americans Duane Solomon and Nick Symmonds finished fourth and fifth.
Pistorius advances to relay final: Double-amputee Oscar Pistorius and his South African teammates are moving on to the 4x400-meter relay final at the Olympics without even finishing their heat.
The man known as "Blade Runner" because of his carbon-fiber prosthetics will get a chance to run for an Olympic medal after officials accepted South Africa's protest over a collision and awarded an extra spot in Friday's final.
In the opening round Thursday, a Kenyan runner knocked into South Africa's Ofentse Mogawane as he made his way around the final bend in the second leg of the race. Mogawane fell and clutched at his left shoulder as the baton rolled away.
Women's 800 meters: Closing in on an Olympic medal three years after being forced to undergo gender tests, Caster Semenya of South Africa won her 800-meter semifinal heat in 1 minute, 57.67 seconds.
The final is Saturday and also will include defending champion Pamela Jelimo of Kenya and former Cal runner Alysia Montano, who qualified fourth at 1:58.42.