Cycling legend Chris Hoy became Britain's greatest Olympian when he powered to a sixth career gold
Cycling legend Chris Hoy became Britain's greatest Olympian when he powered to a sixth career gold, but Chinese athletics icon Liu Xiang crashed to a second successive Olympic heartbreak.
Hoy, 36, won his sixth gold courtesy of victory in the keirin event which allowed him to overtake the five titles garnered by rower Steve Redgrave.
"I'm in shock, you try and compose yourself but it's surreal. I wanted to win gold in front of my home crowd," said Hoy who was in floods of tears at the medal ceremony. "This is the perfect end to my Olympic career."
Hoy's emotional victory helped boost Britain's gold tally to 22, just eight behind the mighty United States, and represented the country's best Olympics performance in more than a century.
Meanwhile, former Olympic 110m hurdles champion and world record holder Liu, who had to withdraw just moments before his opening heat in front of his home fans at Beijing in 2008, saw his 2012 bid crumble in just a split second.
The 29-year-old ploughed into the first hurdle of his opening heat with his left leading leg and crashed heavily to the track.
Liu got up and even hopped down the track to symbolically cross the finish line, also stopping to kiss the 10th and last hurdle, winning warm applause from a stunned 80,000 crowd.
China's athletics team leader in London, Feng Shu Yong, later revealed Liu had possibly snapped his Achilles, a recurrence of a problem which has dogged the 2004 Olympic champion for years.
"The initial diagnosis from the medical staff is that he has a ruptured Achilles tendon... an Achilles injury is almost impossible to recover from fully," said Feng.
Usain Bolt, fresh from running the second-fastest time in history to retain his 100m title on Sunday, began his bid to keep his 200m title by winning his heat in 20.39sec.
"That was an easy run. I am enjoying it," said the Jamaican star. "This is my favourite event so I am looking forward to it."
World 100m champion, and Bolt's compatriot, Yohan Blake also made it through to the next round.
Algeria's Taoufik Makhloufi swept to an astonishing victory in the 1500m, just 24 hours after he was controversially disqualified from the Games for not trying in the 800m.
But he was swiftly reinstated after the emergence of medical evidence which allowed him to run in the 1500m, and he took full advantage of his reprieve to produce a decisive kick on the last lap.
"It was the will of God. Yesterday I was out, today I was in," explained Makhloufi.
Australian Sally Pearson held her nerve to win the women's 100m hurdles with a powerful finish and give her country a welcome boost in the medals table.
The reigning world champion clocked an Olympic record of 12.35sec, edging Beijing Olympic gold medallist Dawn Harper of the United States.
Pearson's victory was Australia's first track and field gold of the London Games and helped her country move to 11th in the table with four golds.
Robert Harting won the men's discus to give Germany their first gold in the discipline for 16 years while Ehsan Hadadi's silver was Iran's first ever Olympic medal in athletics.
Alistair Brownlee won the men's triathlon for Britain in Hyde Park and the equestrian squad clinched team dressage gold at Greenwich.
Victoria Pendleton's dream of ending her Olympic career with a cycling sprint gold was shattered by a defeat to long-standing Australian rival Anna Meares.
Laura Trott gave Britain another gold in the gruelling omnium as the hosts won seven of the 10 golds on the track.
China stayed top of the medals table thanks to golds from Feng Zhe in men's gymnastics parallel bars, Deng Linlin on the women's balance beam and their women's table tennis team.
But their hopes of sweeping all eight diving golds were ended by Russia's Ilya Zakharov who won the men's 3m springboard final ahead of Qin Kai and defending champion He Chong.
In men's football, Mexico advanced to the final for the first time after coming from behind to defeat Asian giants Japan 3-1 and will face Brazil who eased past South Korea 3-0 for the gold medal.