The country's hopes of a first home Olympic gold medal were dashed as cyclist Mark Cavendish missed out on a podium finish amid dramatic scenes.
Thousands of people waving Union Flags lined the route and the nation's hopes had rested on Cavendish to continue the feelgood factor after a UK TV audience of 26.9 million people watched Friday night's stunning opening ceremony.
However, the disappointment of Cavendish's defeat could be shortlived as he is not the only home gold medal contender of the day.
Hannah Miley is preparing to contest the 400 metres individual medley at the aquatics arena.
Miley won a silver medal at last year's World Championships and many will hope she can help Team GB finish the day on a high.
Cavendish had been a favourite at the start of the 250-kilometre race but crowds experienced early nerves as a 12-man breakaway group led by more than five minutes early on.
He lagged behind the front group as the riders re-entered Richmond Park as the race neared its end. But a key moment offered a ray of hope as half a dozen leaders misjudged a corner and crashed out of the race.
Cavendish had already been anointed champion in many people's eyes but earlier in the day he admitted on Twitter: "I am nervous."