Olympic Stadium was packed for the first time since the opening ceremony, and heptathlete Jessica Ennis gave the delirious crowd exactly what it was hoping to see.
Ennis finished the 100-meter hurdles in 12.54 seconds, the fastest time ever in the heptathlon's first event and one of the highlights on a raucous opening day for track and field.
Ennis' time matched Dawn Harper's gold-winning burst in the 100-meter hurdle final at the Beijing Games — and would've been good enough to take that title at the 1992, 1996 and 2000 Olympics.
Poland's Tomasz Majewski (men's shot put) and Ethiopia's Tirunesh Dibaba (women's 10,000 meters) won the first gold medals in track and field, and world champion Carmelita Jeter of the U.S. led the 100-meter heats with a time of 10.83 seconds.
BOXING: Amateur boxing's governing body overturned Errol Spence's loss to Indian welterweight Krishan Vikas, five hours after the defense-minded Vikas had apparently clutched and grabbed his way to a 13-11 victory. After the American team protested the result, AIBA's competition jury reviewed the bout and ruled Vikas had committed nine holding fouls in the third round alone. He also intentionally spit out his mouthpiece in the second round, which should have resulted in at least four points of deductions. Spence advanced into the quarterfinals to face Russia's Andrey Zamkovoy of Russia on Tuesday. If he wins, the American men's team will avoid leaving the Olympics with no medals for the first time ever.
BASKETBALL: Diana Taurasi scored 18 points and Tina Charles finished with a double-double to lead the U.S. women's team to an 88-61 win over the Czech Republic.
BEACH VOLLEYBALL: Defending gold medalists Todd Rogers and Phil Dalhausser of the United States were knocked out of the Olympics by Italy. Jennifer Kessy and April Ross of the U.S. beat Switzerland's Simone Kuhn and Nadine Zumkehr to advance to the quarterfinals of the women's tournament.
VOLLEYBALL: Destinee Hooker scored 19 points and the U.S. women's team clinched the top spot in its pool with a preliminary-round victory over Serbia in straight sets. Logan Tom added 12 points in the 25-17, 25-20, 25-16 sweep. The U.S. will wrap up the preliminary round with a match against Turkey on Sunday.
WATER POLO: Maggie Steffens scored three goals and the U.S. women's team beat China 7-6 in its final preliminary-stage game. The U.S. finished the preliminary round even with Spain at the top Group A with five points. But Spain earned the top spot because of the tiebreaker, and the Americans will play 2012 European champion Italy in Sunday's quarterfinals.
EQUESTRIAN: Rafalca, co-owned by the wife of U.S. presidential hopeful Mitt Romney and ridden by Jan Ebeling, scored 70.243 percent to place 30th out of 50 riders in dressage competition.