‘‘It’s a surreal moment,’’ she said Wednesday at the London Games. ‘‘I got very emotional — you do when you’re representing your country.’’

The two-time world champion went into the competition with the best jump of the season and put down the best mark in the final with 23 feet, 4½ inches on her second attempt. Russia’s Elena Sokolova took the silver medal at 23-2½ and Janay Deloach earned the bronze for the US at 22-7¼.

Now that she’s the reigning Olympic and world champion indoors and out — and is third all time in the US behind Joyner-Kersee and Marion Jones in terms of longest jumps, she is looking to 2016.

‘‘I feel like this is just the beginning,’’ the 25-year-old said.

Semenya advances

Making her Olympic debut three years after being forced to undergo gender tests, Caster Semenya of South Africa finished second in her 800 heat.

Semenya was sidelined for nearly a year while track and field’s governing body decided whether to allow her to compete after she won the 2009 world title at age 18. She was tested and eventually cleared to return to action in 2010, then was the runner-up at last year’s world championships.

She ran her heat in 2:00.71, behind the 2:00.47 run by American Alysia Johnson Montano, the fastest qualifier from the preliminaries. Defending champion Pamela Jelimo won her heat in 2:00.54 to advance with the second-fastest time.

Bolt in 200 final

Usain Bolt of Jamaica won his semifinal heat in 20.18 seconds, moving closer to becoming the first man with two Olympic golds in the 200 meters. Anaso Jobodwana of South Africa finished in 20.27 to reach the final, too. The field will include Bolt’s teammate and training partner, 100 silver medalist Yohan Blake, who barely won the first semifinal heat in 20.01 seconds. Churandy Martina of the Netherlands, Warren Weir of Jamaica and Alex Quinonez of Ecuador also advanced . . . The top qualifier in the women’s 1,500-meter semifinal was Ethiopia’s Abeba Aregawi in 4 minutes, 1.03 seconds. Two US women advanced — Morgan Uceny (4:05.34) and Shannon Rowbury. (4:05.47) . . . In the men’s javelin qualification, Vitezslav Vesely of the Czech Republic had the best toss of the day at 88.34 meters. No Americans made the top 12.

Big day for Eaton

Ashton Eaton, 24, broke Bill Toomey’s 44-year-old Olympic record in the decathlon 100-meter dash, finishing in 10.35 seconds. He ended it with a solid performance in the 400, running it in 46.90. Eaton was first in the long jump, 11th in the shot put and second in the high jump. After five events, Eaton has a 220-point advantage over Trey Hardee of the US. ‘‘You guys keep track of the pace,’’ Eaton said, rolling his eyes. ‘‘I'll keep trying to do my best.’’ In the decathlon, where fatigue is considered another opponent, no lead is safe. The 110-meter hurdles, discus, pole vault, javelin and 1,500 meters await Thursday.

US moving in 5,000

Ethiopia’s Dejen Gebremeskel was the top qualifier in first round of the 5,000 meters in 13 minutes 15.15 seconds. Three Americans move on — Bernard Lagat (13:15.45), Galen Rupp (13:17.56) and Lopez Lomong (13:26.16) . . . Natalya Antyukh of Russia won the women’s 400-meter hurdles, edging world champion Lashinda Demus and narrowly missing the Games record. The 31-year-old Antyukh a bronze medalist in the 400 at the 2004 Athens Olympics, won in 52.70 seconds, just 0.06 outside the Olympic record set by Melaine Walker in Beijing. Demus took silver in 52.77 and Zuzana Hejnova of the Czech Republic got the bronze medal in 53.38 . . . Chinese hurdler Liu Xiang needs an operation on his right Achilles’ tendon. The 2004 Olympic champion was injured Tuesday during the 110-meter hurdle heats at the London Olympics . . . Defending Olympic pole vault champion Steve Hooker of Australia qualified for Friday’s final with a jump of 5.5 meters, or 18 feet ½ inches, during Wednesday’s preliminaries . . . The US men’s 4 x 100-meter relay team for Friday’s preliminaries includes former Florida running back Jeff Demps, Trell Kimmons, 100-meter finalist Ryan Bailey, and Darvis Patton. The Americans likely are saving Justin Gatlin and Tyson Gay for Saturday’s final . . . Former world record-holder Asafa Powell is out the sprint relay for Jamaica after pulling his left groin during the 100-meter final . . . Britain’s Sophie Hitchon set a world record in the preliminaries of the women’s hammer throw with a toss of 71.98 meters.

. . . St. Kitts officials said sprinter Tameka Williams, who was sent home from the games for doping, took a stimulant known ast “Blast Off Red’’ which increases performance in animals . . .