An embarrassing shortage of security guards, fears over airport queues and questions about the capital's creaking transport system have overshadowed preparations for the Games.
And two stories from American and Australian athletes did little to dispel the sense of farce.
US 400m hurdler Kerron Clement, twice a world champion, claimed he spent four hours on a bus after the driver got lost on the way to the London 2012 Olympic Village.
Games organisers are expecting a busy day with hundreds of athletes checking in, but it has not all been smooth running according to Clement - who takes on Dai Greene, Great Britain's current world champion, in the one-lap hurdles next month.
"Um, so we've been lost on the road for 4hrs. Not a good first impression London," he tweeted.
"Athletes are sleepy, hungry and need to pee. Could we get to the Olympic Village please?"
The American track and field squad will spend the next three weeks at their training base in Birmingham but needed to travel to the Olympic Park to pick-up their all-important accreditation.
A bus of 30 Australian officials and medics, meanwhile, took the scenic route through London when their bus driver forgot the route and admitted not knowing how to work the on-board GPS system.
"It would have been a great tourist trip if that is what you are here for," said Australian official Damian Kelly.
"He admitted this was the first time he had taken the route and no one had taught him how the navigation system works because it operates off GPS.
"One of the doctors on board got it working for him, but then the Olympic Village hadn't been loaded into the system and everyone was trying to find the name of the street that the village was in. In the end another physio got out his iPhone and gave directors to the bus driver via his phone."
Extra soldiers were drafted in to help police the Games after private security firm G4S said it had run out of time to train all its newly recruited staff. The company's share price fell sharply on Monday.
Less than two weeks before the opening ceremony on July 27, Prime Minister David Cameron said the G4S shambles would not compromise Britain's largest peacetime policing exercise.
"We had contingency plans, we are using those contingency plans and we will do whatever it takes to deliver a safe and secure Games," Cameron said.
The security fiasco dominated the headlines over the weekend and raised fears that Britain would struggle to cope with the Games.
A cartoon in the Daily Telegraph newspaper showed a red-faced, overweight runner wearing a G4S vest, complaining: "I didn't realise I had to run all the way to the end."
Some 12,500 police will be on Olympics duty each day, backed up by soldiers, fighter jets and missile batteries on the top of apartment blocks near the Olympic site in East London.
Security chiefs said they had prepared for threats on the scale of the September 11 attacks in 2001. Four British Islamist suicide bombers killed 52 people on three trains and a bus in London on the day after the city was awarded the Games in July 2005.
Heathrow Airport was ready for its busiest day on record, while the Olympic Village opened its doors to the first athletes.
The first arrivals at an airport notorious for queues at security checks and passport control said everything had gone smoothly.
"I was expecting a three-hour queue like everyone said. It took not even five minutes. It was flawless - good job London," said John Retsios, 36, who had flown from New York with the US Modern Pentathlon team.
Airport operator BAA Plc, owned by Spain's Ferrovial , said it expected a record 237,000 passengers to use Heathrow on Monday, including 335 athletes. The busiest day for arriving athletes is expected to be July 24.
The first section of road reserved for Olympic athletes and officials began operating on Monday, when one lane of the motorway linking Heathrow with the western edge of the capital was closed to all non-Olympic traffic.
It will form part of a 30-mile network of road lanes designed to whisk 82,000 athletes and officials through London's notoriously congested streets. Critics have nicknamed them 'Zil lanes' after the roads reserved for the limousines of senior officials in the old Soviet Union.
London Mayor Boris Johnson said the city was ready for the Games, the transport system would cope and visitors would be safe.
"When the opening ceremony begins, then a lot of these issues that we are currently discussing will melt away," Johnson told BBC television.
"There is a bit of 'pre-curtain up' jitters and casting around for things to talk about."