Andy Murray rode a wave of British euphoria Sunday as he routed Roger Federer for Olympic tennis gold, while Usain Bolt and Yohan Blake prepared for a 100m sprint billed as the fastest race in history.

A day after the hosts clocked up six golds -- their best Olympic performance in more than a century -- Murray kept the shocks rolling as he overpowered Federer 6-2, 6-1, 6-4 at Wimbledon.

Just four weeks after losing to the Swiss at the same venue, denying Britain a first men's grand slam singles win in 76 years, Murray was crying tears of joy as he climbed into the stands to celebrate with his girlfriend and mother.

"This is one of the biggest wins of my life," Murray said. "I have had a lot of tough losses in my career and this is the best way to come back from the Wimbledon final."

Almost incredibly, Murray can win two golds in one day when he partners Laura Robson in the mixed doubles final. That would match Serena Williams, who won the women's doubles with her sister Venus, a day after her singles triumph.

The Americans beat Andrea Hlavackova and Lucie Hradecka 6-4, 6-4 to claim their third Olympics doubles title.

"There's something about standing next to Venus and holding that gold medal," Serena said. "Three times we've played, three times we've got the gold medal. So we are pretty stoked about it."

Britain's Ben Ainslie claimed his place in history as he won his fourth consecutive sailing gold, in the Finn class, making him the sport's most successful Olympian. But he ruled out trying for a fifth title.

"You can never say never but I don't think I can sail one of these again, it's killing my body so I don't think you will see me in Rio," Ainslie said in Weymouth, on Britain's south coast.

Mid-way through day nine, China were back on top of the medals table with 28 golds to 27 for the United States. Britain were in third place with 16.

But Sunday's action will mostly serve as a warm-up for the day's main event, when Blake, Asafa Powell and Tyson Gay take aim at Bolt's 100m title, earned in world-record time four years ago in Beijing.

The starting line-up for the showpiece, the climax of the day's action, could feature all of the four fastest men in history.

Jamaican defending champion Bolt strolled through his opening heat on Saturday, but he faces a menacing threat to his supremacy from compatriot and world champion Blake.

With former world record-holder Powell and American duo Gay and Gatlin in the field, the stage is set for a classic sprint duel.

"I am the Olympic champion and I have to show the world I am the best," Bolt, 25, in a bullish eve-of-Games statement of intent.

At the other end of the distance spectrum, the women's marathon was won by Ethiopian Tiki Gelana in the opening athletics medal of the day.

After a gruelling battle through London's streets which swept past some of the British capital's most iconic landmarks, Gelana raced home on The Mall in an Olympic record time of 2hr 23min 7sec.

Kenya's Priscah Jeptoo won the silver with Russia's Tatyana Petrova Arkhipova taking bronze.

Elsewhere, women's boxing made its debut in Olympic competition with the opening bouts in the women's flyweight and lightweight categories.

The first ever bout saw Russia's Elena Savelyeva defeat North Korea's Kim Hye-Song on points.

China completed the first clean-sweep of all five badminton gold medals, with Lin Dan winning a thrilling men's singles final against Malaysian rival Lee Chong Wei, and Cai Yun and Fu Haifeng triumphing in the men's doubles.

Chinese gymnast Zou Kai successfully defended his Olympic men's floor title, Romania's Sandra Izbasa won the women's vault and Hungary's Krisztian Berki was victorious in the men's Olympic pommel horse.

A total of 23 medals will be decided on Sunday, culminating in the men's 100m final at 9:50pm (0850 GMT).