LONDON - Serena and Venus Williams won the women's doubles tennis title and Tiki Gelana of Ethiopia held off her two closest rivals to win a rainy women's marathon on Sunday at the London Olympics.
After Britain won six gold medals on Saturday, including three in an hour at the athletics stadium, the celebrations could continue Sunday if Andy Murray beats Roger Federer for the singles gold medal in a rematch of their Wimbledon final of a month ago on the same Centre Court. That time, Federer won his seventh Wimbledon title.
Before Murray and Federer began their final, the Williams sisters became the first tennis players to win four Olympic gold medals, defending their Beijing 2008 doubles title with a 6-4, 6-4 victory over Andrea Hlavackova and Lucie Hradecka of the Czech Republic.
Serena made it a perfect Olympics, playing under the roof on a rainy afternoon at the All England Club a day after she dominated Maria Sharapova 6-0, 6-1 for singles gold. She joined Steffi Graf as the only women to complete the Golden Slam — winning the Olympics and the four majors.
In the marathon, which started and ended at Buckingham Palace, Gelana finished in a time of 2 hours, 23.07 seconds, holding off Priscah Jeptoo of Kenya by five seconds. Tatyana Petrova Arkhipova of Russia took the bronze.
Britain's Ben Ainslie won his fourth straight gold medal and fifth games medal overall, making him the most successful sailor in Olympic history.
Ainslie eclipsed Denmark's Paul Elvstrom as the most successful sailing Olympian. Elvstrom won four straight gold medals from 1948-60, including three in the Finn class.
All Ainslie had to do was finish ahead of Denmark's Jonas Hoegh-Christensen, who led the Olympics regatta from Race 1. The Dane finished 10th and took the silver.
Earlier, Fredrik Loof and Max Salminen of Sweden upset defending champions Iain Percy and Andrew Simpson of Britain to win the gold medal in sailing's Star class.
In the first of three apparatus finals Sunday in gymnastics, Zou Kai added another gold medal to his collection, defending his Olympic title on men's floor exercise Sunday. It was the fifth gold medal for China's Zou, who has one from last week's team competition and won three in Beijing.
Lin Dan of China become the first man to retain the Olympic badminton singles title, beating Malaysian archrival Lee Chong Wei 15-21, 21-10, 21-19.
Defending champion Jin Jong-oh of South Korea won his second shooting gold medal in London, overtaking compatriot Choi Young-rae by 0.5 point on his last shot in the 50-meter pistol final.
In Sunday night's 100-meter final at the Olympic track, Usain Bolt, who swept the 100, 200 and 4x100 in Beijing, each in world-record time, faces tough competition from his training partner Yohan Blake.
Blake, the world champion, beat Bolt in the 100 and 200 at the Jamaican Olympic trials.
Britain will be aiming to continue its dominance at the London Velodrome, where the hosts have won four of the five gold medals awarded in track cycling.
In early racing, omnium world champion Glenn O'Shea of Australia moved into first place overall with two races remaining. O'Shea was third overnight after finishing third in the flying lap and the elimination race while ending eighth in the points race.