International Olympic Committee chiefs are satisfied the 2012 Games will not be afflicted by the same delays that have held up the new Wembley Stadium.
Work to build the new Olympic sites has already begun
Inspectors ended a two-day visit to London on Friday and said they were "encouraged" by the progress so far.
IOC commission chairman Denis Oswald said: "We have no fear that the projects will not be ready in time.
"We are encouraged by the momentum and we are convinced that London can achieve what they have promised."
The IOC will inspect venues once a year until 2008, when progress will be subject to scrutiny every six months.
The commission did discuss proposed changes to the aquatic centre, which will need its design altered if it is to stay within its £75m budget.
The president of the International Swimming Federation, Mustafa Larfaoui, is on the commission and was apparently satisfied with the answers given.
"There have been some changes but mainly regarding the outside and aesthetics of the aquatic centre, but this would in no way reduce its technical value," added Oswald.
Oswald believes London are two or three years ahead of Athens in terms of their preparations but said the 2012 Games were a more ambitious project.
"This project is certainly very ambitious, but there must be a balance between your ambition and your resources," said Oswald.
"But London certainly has the resources and the technical ability."
London mayor Ken Livingstone said on Thursday that 80% of the land required for the Games had already been acquired.
"We should have a final decision on the compulsory purchase orders by November which means nothing is standing in the way of work beginning on schedule," he added.
London Organising Committee chairman Lord Coe also revealed that a football team could move into the Olympic Stadium after the Games had finished.
Organisers had previously suggested that the stadium would be reduced in capacity to 25,000 and used as a venue for athletics after the Games.
Meanwhile, Culture, Media and Sport Secretary Tessa Jowell, insisted that the cost of staging the Games would be kept in check.
"We are carrying out as review of all the costs, and that will be a continuing discipline," she said.
"We expect some costs to rise, but others will come down. We are right on top of that process."