Kayla Harrison tried to keep it together. Once the national anthem started, so did the tears.

Harrison defeated Britain’s Gemma Gibbons to win the United States’ first judo gold medal in Olympic history, taking the 78-kilogram title.

The 22-year-old Middletown, Ohio, native who lives in suburban Boston went to the medal podium determined not to cry. After one note of "The Star-Spangled Banner," she succumbed.

"I’m just so honored to be America’s first gold medalist, and so happy to realize my dream," she said.

TENNIS

Wimbledon champion Roger Federer beat American John Isner 6-4, 7-6 (5) and will play No. 8-seeded Juan Martin del Potro in the semifinals.

Serena Williams, another reigning Wimbledon champion who is seeking her first Olympic singles medal, advanced by beating former No. 1 Caroline Wozniacki of Denmark 6-0, 6-3. Williams’ opponent in the semifinals today is top-seeded Victoria Azarenka, who beat Angelique Kerber 6-4, 7-5.

Russians Maria Sharapova and Maria Kirilenko will meet in the other women’s semi.

Novak Djokovic also advanced on the men’s side and next plays Britain’s Andy Murray.

CYCLING

Germany’s Miriam Welte and Kristina Vogel won gold in sprint track cycling after the Chinese duo of Guo Shuang and Gong Jinjie was disqualified for a lane change in the final.

Britain broke its own world record set earlier in the day to win its second straight gold medal in the men’s team sprint. The team of Philip Hindes, Jason Kenny and Chris Hoy posted a time of 42.600 seconds.

BEACH VOLLEYBALL

All four American teams — two in the men’s tournament and two in the women’s — finished the round-robin atop their pools, with defending gold medalists Todd Rogers and Phil Dalhausser beating the Czech Republic in the finale.

Americans Jennifer Kessy and April Ross finished 3-0 with a 21-19, 19-21, 19-17 victory over Spain.

WATER POLO

Tony Azevedo scored four goals and the U.S. men’s team beat Britain 13-7 to remain undefeated in London.

The Americans are on top of Group B with six points, one ahead of Serbia with two preliminary stage matches to go.

BOXING

The American skid reached seven straight bouts with narrow defeats for lightweight Jose Ramirez and middleweight Terrell Gausha. Only welterweight Errol Spence and flyweight Rau’shee Warren — who hasn’t fought yet — are still alive.

Ramirez fell 15-11 to Uzbekistan’s Fazliddin Gaibnazarov, while Gausha was locked in a tight one with Beijing bronze medalist Vijender Singh of India before dropping a 16-15 decision.

ROWING

The United States defended its title in the women’s eight, maintaining its six-year dominance of the high-profile event.

The Americans won in a time of 6 minutes, 10.59 seconds. Canada finished a half-length behind in second and the Netherlands took the bronze. The U.S. hasn’t lost a competitive race in the eight since winning the world title in 2006.

SAILING

British star Ben Ainslie got his first victory at the London Olympics in Race 7 in the Finn class in strong winds and big seas on the English Channel. He followed it up by passing Jonas Hoegh-Christensen just before the finish in Race 8 to take third.

Ainslie sliced Hoegh-Christensen’s lead from 10 points to three with two races to go before the medals race.

CANOE

Britain took the top two spots in canoe slalom, upsetting three-time defending champions Pavol and Peter Hochschorner of Slovakia.

Tim Baillie and Etienne Stott won the gold, followed by teammates David Florence and Richard Hounslow.

Emilie Fer of France was the surprise winner in women’s kayak slalom.