The nation's hopes of a golden start to the Olympics suffered a setback when cyclist Mark Cavendish failed to land a medal.

The sprinter began the day as one of Team GB's best hopes for a gold and thousands of people lined the route of the men's road race through Surrey into central London.

While the 250km route was packed with spectators, the Games' organisers Locog launched an investigation into empty seats at venues on the Olympic Park. In the Aquatic Centre - which saw a surprise visit by the Queen - there were hundreds of empty seats despite all public tickets having been sold.

A Locog spokesman said: "We are aware that some venues have empty seats this morning. We believe the empty seats are in accredited seating areas, and we are in the process of finding out who should have been in the seats and why they weren't there."

Cavendish missed out on a podium finish amid dramatic scenes, coming in almost a minute behind the leaders.

He told the BBC of his frustration at other teams' "negative tactics" which blocked his efforts. But he added: "We may not have won a medal but I'm completely proud of my team and completely proud of my country."

Meanwhile, Andy and Jamie Murray crashed out in the first round of the Olympic men's doubles in a very tight battle with Austria's Jurgen Melzer and Alexander Peya. The pair were cheered on by a raucous crowd on Court Two at Wimbledon and edged the first set but, despite being twice a break ahead in the decider, they could not close it out and went down 5-7 7-6 (8/6) 7-5 after two hours and 23 minutes.

Despite the setbacks, spirits remained high following Friday night's spectacular opening ceremony. A UK TV audience of 26.9 million people watched the ceremony, the biggest TV audience in the UK for 14 years, according to the BBC.

The Queen - who stole the show after making her movie debut alongside James Bond before supposedly parachuting into the stadium - said she was delighted to have taken part.

Oscar-winning director Danny Boyle won international plaudits for the ceremony. Germany's Bild newspaper raved: "A gigantic spectacle. What a show!" Australia's Sydney Morning Herald said it was "an unforgettable start" and "breathtaking".