"It still hasn't sunk in yet that I'm Olympic champion," Merritt, 27, said.
Reese leaps to gold. Brittney Reese, a two-time world champion, became only the second American woman to win the long jump in the Olympics, leaping 23 feet, 41/2 inches on her second attempt. Jackie Joyner-Kersee gave the United States its other gold in 1988.
Silver in women's hurdles. World champion Lashinda Demus of the United States earned a silver medal in the women's 400 hurdles after finishing second to Russia's Natalya Antyukh. Zuzana Hejnova of the Czech Republic was third.
Decathlon domination. Ashton Eaton started off the decathlon with an Olympic-best performance in the 100 meters and kept up the momentum, jumping out to a big lead after the first day.
Eaton had a 220-point advantage over fellow American Trey Hardee through five events.
Eaton began by breaking Bill Toomey's 44-year-old record in the 100-meter dash, finishing in 10.35 seconds. He ended it with a solid performance in the 400. In between, Eaton finished first in the long jump, 11th in the shot put, and second in the high jump.
Semenya qualifies. Making her Olympic debut three years after being forced to undergo gender tests, Caster Semenya of South Africa finished second in her 800 heat in 2 minutes, 0.71 seconds, behind the 2:00.47 run by Alysia Johnson Montano of the United States.
Algerian takes advantage. First they told him to leave. Then they invited him back. Now, he has gold.
Kicked out of the London Olympics for presumably not trying hard enough in another event, Algeria's Taoufik Makhloufi got a second chance after a doctor took his side.
He cashed in on that opportunity and won the 1,500 meters in 3:34.08, beating Leonel Manzano of the United States by 0.71 seconds. Abdalaati Iguider of Morocco got the bronze in 3:35.13.
"Yesterday I was out," Makhloufi said. "And today I was in."
On Monday, the race referee in the 800 meters, Makhloufi's other event, kicked him out of the Olympics for "failure to compete honestly with bona fide effort" after breaking slowly and pulling out of the race on the first lap.
But the Algerian coaches insisted Makhloufi pulled out of the 800 because of a left knee injury. When a doctor examined the runner and said the injury was legit, officials revoked the DQ and allowed him to start in the 1,500.
Manzano's silver was the first medal for the United States in the 1,500 since Jim Ryun won silver in Mexico City in 1968. Matthew Centrowitz of the United States finished fourth, 0.04 seconds from bronze.