Prime Minister David Cameron insisted Thursday that Britain would deliver a memorable Olympics after US presidential hopeful Mitt Romney backtracked on barbed comments he made about the London Games.
With excitement mounting on the eve of the opening ceremony, Prince William, his wife Catherine and Prince Harry welcomed the torch to Buckingham Palace where tens of thousands of spectators had gathered.
But Romney, in London to attend Friday's opening of the Games, said the preparations had been "disconcerting", pointing to the failure of a private security contractor to provide the number of guards it had promised.
The Republican candidate also wondered aloud whether the British public would get behind the first Games to be held here since 1948.
On the eve of the Olympics, Cameron said security "matters more than anything else", and said he was convinced the Games would prove that Britain could stage a world-class event.
Cameron also said he was sure Britons would get behind the Games despite an economic downturn -- and took an apparent swipe at Romney's past as head of the 2002 Winter Olympics in Salt Lake City.
"We are holding an Olympic Games in one of the busiest, most active, bustling cities anywhere in the world," Cameron said.
"Of course it's easier if you hold an Olympic Games in the middle of nowhere."
Cameron said he would take personal responsibility for the security of the Games, which are guarded by Britain's biggest ever peacetime force.
Britain has deployed an additional 4,700 troops in recent days to make up the shortfall in guards supplied by giant contractor G4S, taking the total military deployment to 18,200.
Romney told NBC News on Wednesday that "the stories about the private security firm not having enough people, the supposed strike of the immigration and customs officials -- that obviously is not something which is encouraging".
It was "hard to know just how well it will turn out", he added.
But he struck a more diplomatic note after talks with Cameron later.
"I am very delighted with the prospects of a highly successful Olympic Games," Romney said.
"What I have seen shows imagination and forethought and a lot of organisation. I expect the Games to be highly successful."
The US team meanwhile seemed happy with the conditions in London.
"Our experience has been nothing but positive," said Scott Blackmun, US Olympic Committee chief executive officer.
"We're not seeing any indication of anything less than great enthusiasm from people on the street."
The rising excitement was displayed at Buckingham Palace where thousands cheered on charity worker Wai-Ming Lee as he picked up the torch under the gaze of Prince William.
Lee, 38, said the experience "was exhilarating and over too soon" and revealed that Prince William had joked to him "don't drop it".
However, spirits were later dampened when Great Britain's footballers conceded a late goal in their opening match of the Games against Senegal.
Craig Bellamy had put the hosts into an early lead, but Moussa Konate struck in the 82nd minute to ensure the spoils were shared.
Meanwhile, the Games was rocked by a doping scandal after Greece's world indoor high jump champion Dimitris Chondrokoukis was barred for failing a drugs test.
His coach and father Kyriakos Chondrokoukis said his son had tested positive for stanozolol, the steroid used by disgraced sprinter Ben Johnson at the 1988 Seoul Olympics.
Meanwhile, Games organisers tried to downplay a mix-up which saw North Korea's women football team walk off the pitch in an embarrassing start to the competitive action at the Games.
The International Olympic Committee apologised to the North Korean delegation after its players were shown on giant screens next to South Korea's flag, at their opener against Colombia on Wednesday at Hampden Park in Glasgow.
IOC president Jacques Rogge described the incident as "most unfortunate".
"This was an honest mistake, honestly made," Cameron said."
