Britain sought to reassure the world on Tuesday that a last-minute security blunder that forced it to call up thousands of extra troops for next week's Olympics Games would not compromise people's safety.
With 10 days to go until the start of the Games, an embarrassing shortage of security guards, fears over airport queues and London's creaking transport system have eclipsed an otherwise smooth run in to the world's biggest sporting event.
The final countdown got off to a shaky start this week as athletes arriving in Britain reported traffic delays in getting to London's Olympic village, and a protest by taxi drivers in central London highlighted people's frustrations.
And as parliament launched an inquiry into why the world's biggest security firm, G4S, failed to recruit enough guards for the Olympics, London's mayor admitted that "things could go wrong" with transport during the Games.
But Sebastian Coe, chairman of the London Olympic organising committee (LOCOG) and a middle-distance Olympic gold medal winner, promised there would be no more hiccups.
"We are ready. We are ready on security," he told reporters. "This has not, and nor will it impact on the safety and security of these Games, that of course is our number one objective."
Appearing in front of a hostile parliamentary committee, G4S chief Nick Buckles admitted his handling of the security scandal had embarrassed the British government and left his company's reputation in tatters.
Britain has already spent 9 billion pounds ($14 billion) on the Games and expectations are high after the country put on its biggest peacetime security and transport operation.
Yet London is already showing signs of strain, inviting awkward comparisons with the 2008 Olympic Games in Beijing that drew worldwide praise for its lavish ceremonies, sleek infrastructure and a gleaming new airport.
London Mayor Boris Johnson, usually an ebullient optimist, said he did not expect perfection.
"There will be imperfections, there will be things going wrong," he was quoted as saying by domestic media. "But this is a ginormous operation."
Police said officers from across Britain had been deployed earlier than planned to fill in the security gap.
"This is a huge and complicated logistical project and some things aren't going to run exactly as we expect them to. The test is how we respond to that," said a spokesman for Prime Minister David Cameron.
"We have contingency plans in place. We have already called on an additional reserve of military personnel and we will make sure we have the necessary people in place."
At the Olympic Park site in east London, last-minute preparations were underway, with forklift trucks shifting building materials into place and workers putting the finishing touches to roads around the main stadium.
Soldiers staffed security gates for the small number of visitors to the main media centre on Tuesday, while hundreds of uniformed staff from caterers to guides milled around offering smiles and advice to lost reporters.
As the first wave of Olympic athletes and visitors began pouring into Britain, much of the focus is now on how London's already strained transport network will cope with the influx.
No serious trouble has been reported so far, with Heathrow airport operating smoothly despite the fears in the build-up to the Games.
Athletes from the United States and Australia however grabbed media attention this week when they used social media to describe how their drivers got lost on their way to the Olympic village from Heathrow.
"Um, so we've been lost on the road for 4hrs. Not a good first impression London," Kerron Clement, the U.S. 400 metres hurdles champion, said on Twitter. "Athletes are sleepy, hungry and need to pee. Could we get to the Olympic Village please."
Motorists and commuters are bracing for the worst, saying special traffic lanes prioritising Olympic-related traffic in London could cause traffic chaos.
Hundreds of London's trademark black cabs queued up outside the parliament building in protest against the expected jams.
"How are we supposed to do our job?" said Lee Osborne, one of the protest organisers. John, a cabbie of three years, added: "If they let us drive people round you wouldn't have all the Australians getting lost."
But above all, bad weather remained a major concern after weeks of incessant rain in London.
"I spent most of Sunday in the Olympic stadium watching a goodly chunk of our 15,000 volunteer cast heroically rehearsing in the rain," said Coe. "I've joked in the past about the challenge of putting a roof across the whole country but this is actually proving quite a challenge to us."