LONDON — After hosting a dazzling opening ceremony Friday night, Britain got off to a shaky start on the first full day of action when favored cycling star Mark Cavendish finished 28th in the road race.

LONDON — After hosting a dazzling opening ceremony Friday night, Britain got off to a shaky start on the first full day of action when favored cycling star Mark Cavendish finished 28th in the road race.

Kazakhstan's Alexander Vinokourov, who has said he will retire from cycling after the games, won gold. Rigoberto Uran of Colombia took silver, and Alexander Kristoff of Norway won a mass sprint for the bronze.

"The guys all sat there in the tent absolutely spent. We did everything we could," Cavendish said afterward. "We didn't expect any help. We rode the race we wanted to ride."

Wimbledon champions Roger Federer and Serena Williams each won their opening matches — one struggled, one didn't.

Federer, a four-time Olympian, overcame a jittery patch and beat Alejandro Falla of Colombia 6-3, 5-7, 6-3. The top-ranked Swiss star was a point from victory in the second set, then lost three of his next four service games. But he recovered in time to avoid the upset.

U.S. First Lady Michelle Obama watched from the front row of Williams' box as the fourth-seeded American beat former No. 1 Jelena Jankovic of Serbia 6-3, 6-1 on Centre Court.

Cavendish and his troubles aside, his countrymen got off to a terrific start in men's gymnastics — almost as good as the United States.

While perennial powerhouses China and Japan bobbled and wobbled their way through qualifying, the Americans proved they really do have the goods to contend for the gold medal. They didn't count a single fall, and their final score of 275.342 is almost three points ahead of Britain.

Britain, which was only good enough to send two gymnasts to Beijing four years ago, got a spectacular pommel horse by Louis Smith and finished with a score of 272.420.

"It's just a dream competition really," said Smith, the British captain.

Women's Basketball

Maybe it was first-game nerves or a hangover from the opening ceremony. But the U.S. had to overcome a sloppy performance to post an 81-56 victory over Croatia in its first game.

The U.S., which got back to its hotel at 3 a.m. after the kickoff party, struggled for the first three quarters before winning its 34th consecutive Olympic game.

Next up for the Americans is Angola, which lost to Turkey 72-50 in its Olympic debut.

The Czech Republic lost their pool opener, falling to China 66-57. In another early game, Russia rallied past Canada 58-53. France beat Brazil 73-58.

Beach Volleyball

The Olympics' sexiest sport opened with a raucous debut, mixing in a little local flair with all of the more traditional trifles that have made the event one of the most sought-after tickets in London (though Sir Paul McCartney managed to get one for the afternoon session).

A dance team in bathing suits jiggled for the sold-out crowd during timeouts, while rock music nearly drowned out the pealing of Big Ben.

Located just inside the gate used by the queen — and only the queen — to ride up to Buckingham Palace, the beach volleyball venue offers views of the London Eye, the Big Ben clock tower and 10 Downing Street.

Americans Kerri Walsh Jennings and Misty May-Treanor, who are trying for a third consecutive gold medal, beat Australians Tasmin Hinchley and five-time Olympian Natalie Cook in the final match 21-18, 21-19. The No. 2 U.S. men's team of Sean Rosenthal and Jake Gibb needed just 33 minutes to put away South Africans Freedom Chiya and Grant Goldschmidt.

Boxing

Americans Joseph Diaz Jr. and Terrell Gausha posted impressive victories on the first day of the boxing competition.

Diaz looked sharp in a 19-9 victory over Ukraine bantamweight Pavlo Ishchenko in the tournament's opening bout, while Gausha knocked down Armenian middleweight Andranik Hakobyan twice in the final 7 seconds of his middleweight bout, winning by stoppage with no time on the clock.

Georgian middleweight Merab Turkadze forfeited his evening bout after failing to make weight, allowing Algeria's Amine Mohammed Ouadahi to win by walkover.

Table Tennis

Warren Buffett and Bill Gates will be thrilled when they get the news: 16-year-old American Ariel Hsing is into the second round in Olympic table tennis.

She defeated Yadira Silva of Mexico in four straight games on the opening day. With none of the top 16 players and favored Chinese entering competition until the third round, Hsing made the most of her first Olympic appearance.

Buffett met Hsing when she was only 9 and two years later invited her to play against shareholders at Berkshire Hathaway's annual meeting. She returned earlier this year after winning a spot on the U.S. team and took a few points off Buffett and Gates.

Rowing

The United States and Germany won heats in the blue-riband men's eight, leaving a host of top crews to vie for places in the final.

Only one crew progresses from each heat. The Germans, unbeaten in three years, finished a half length ahead of Britain at Dorney Lake. Olympic champion Canada came in last in a race fit for the final.

The U.S. beat Australia by a half length to reach Wednesday's final, which should be one of the regatta highlights.

Equestrian

Australia took the early lead in Olympic equestrian eventing at Greenwich Park, with Germany and the United States close behind.

Half the 50 riders rode their dressage test that starts the three-phase competition, which includes cross-country and show jumping.

In the individual competition, Germany's Ingrid Klimke had a sparkling dressage test to score 39.3 penalty points, followed by teammate Dirk Schrade on King Artus with 39.8 and Mary King of Britain with 40.9 on Imperial Cavalier.

Several teams, including favorites Britain and New Zealand, did not have a complete rotation of three riders, so team standings are still preliminary.

American riders included Boyd Martin of Cochranville, Pa., scoring 50.7 penalty points on Otis Barbotiere; Karen O'Connor of The Plains, Va., earning 48.2 on Mr. Medicott; and Tiana Coudray of Ojai, Calif., with 52.0 on Ringwood Magister.

Fencing

Elisa Di Francisca completed an Italian sweep in the Olympics' individual foil, winning the gold 12-11 in overtime against countrywoman Arianna Errigo.

Errigo beat three-time defending champion Valentina Vezzali 15-12 in the semifinals, denying her Italian teammate a chance to become the first female athlete to win individual gold at four consecutive Olympics.

The 38-year-old Vezzali won a tense battle for bronze, 13-12 against top-ranked Nam Hyun-Hee of South Korea.

Judo

Sarah Menezes of Brazil and Arsen Galstyan of Russia won the first two golds in the judo competition.

The second-ranked Menezes beat defending Olympic champion Alina Dumitru of Romania in the women's 48-kilogram final. Galstyan defeated one of the 60-kg favorites, Hiroaki Hiroaka of Japan, for his first Olympic medal.

Shooting

South Korean marksman Jin Jong-oh won the 10-meter air pistol gold medal, improving on his silver in Beijing. Italian police officer Luca Tesconi won the silver, and Andrija Zlatic of Serbia took the bronze.

Top-ranked Yi Siling of China captured the first gold medal of the Olympics in the women's 10-meter air rifle at Royal Artillery Barracks. Sylwia Bogacka of Poland took the silver for her first major medal, and Yu Dan of China went home with the bronze.

Badminton

Former champion Taufik Hidayat of Indonesia opened his last Olympics with a comfortable 21-8, 21-8 win over Petr Koukal of the Czech Republic in group play.

In women's action, gold medal contender Li Xuerui of China handled Claudia Rivero Modenesi of Peru 21-5, 21-6 in 22 minutes.

Handball

Defending champion Norway lost 24-23 to France in their Group B opener in women's handball.

Three-time Olympic champion Denmark got a victory in Group B, edging Sweden 21-18.

Weightlifting

Wang Mingjuan of China won the first gold medal of the weightlifting competition, taking the women's 48-kilogram title with a total weight of 205 kilograms. The four-time world champion dominated the competition.