Five things to know about Saturday, Day 8 of the London Olympics:
_ Double-amputee Oscar Pistorius advances in his Olympic debut in the 400.
_ Usain Bolt, Yohan Blake, Tyson Gay and Justin Gatlin advance to 100 meters semifinals.
_ Women's triathlon gives London Olympics its tightest finish yet.
_ Serena Williams and Maria Sharapova play for gold in women's singles at Wimbledon.
_ Former 100-meter world champion Kim Collins dropped from his race after being disciplined by the St. Kitts and Nevis team.
The man known as the "Blade Runner" finally got his Olympic moment Saturday when he took to the starting line of the 400-meter heat and easily advanced to the semifinals.
Oscar Pistorius worked for six years to get the chance to run, and he became the first amputee to compete in track in the Olympics. With 80,000 fans watching him make history, he cruised past a couple of opponents in his heat to advance to Sunday night's semifinals.
"I found myself smiling in the starting block," Pistorius said. "Which is very rare in the 400 meters."
Pistorius was born without fibulas and his legs were amputated below the knee before he was 1. He runs on carbon-fiber blades and fought to get to the starting line. He had friends and family in the stands _ including his 89-year-old grandmother, who was carrying the South African flag.
"It's very difficult to separate the occasion from the race," Pistorius said.
Attention quickly turned to the preliminary heats in the 100 meters, where defending Olympic champion Usain Bolt advanced to the semifinals. He overcame a slow start to win his heat in 10.09 seconds. Yohan Blake, who beat Bolt in Jamaica's trials, finished his heat a fraction faster at 10.0 seconds. Justin Gatlin of the United States also advanced.
It was the busiest day yet at the London Olympics with 25 medals on the line. Serena Williams advanced easily to Saturday's women's final at Wimbledon against Maria Sharapova where she looked to turn her first Olympic medal into gold.
Women's triathlon also provided the tightest ending yet in London when Nicola Spirig of Switzerland and Lisa Norden of Sweden crossed the line in a photo finish. Spirig won the gold after a few minutes where both women celebrated.
Jamie Lynn Gray of the United States won the gold medal in women's 50-meter three-position rifle shooting, setting two Olympic records along the way.
The American's final score was 691.9 points, topping the previous total Olympic mark of 690.3 set by China's Du Li at the 2008 Beijing Games. She clinched gold on her final shot with a 10.8 _ just 0.1 off what would have been perfect.
Rowing wrapped up its regatta in Windsor with Britain adding two more gold medals in the men's four and the lightweight women's double sculls Saturday, leaving the host nation atop the rowing medals table. The British finished with nine medals _ four golds, two silvers and three bronzes _ in topping its record total of eight from the 1908 Olympics, which also were held in London.
Kim Collins was the 2003 world champion and flag-bearer for St. Kitts and Nevis at the opening ceremony. He also still is entered in the 200 and the 4x100 relay and could still run. But team spokesman Lester Hanley told The Associated Press that Collins would not run in his heat after breaking team rules by leaving the athletes village.
"Kim has not been in camp the last couple of days," Hanley said in a telephone interview.
Collins posted messages on his Twitter account Saturday, saying "My fans. I won't lie. Won't be running later tonight."