Boris Johnson has welcomed a cost-cutting move to relocate the Olympic gymnastics and badminton events to Wembley Arena.
Olympics chiefs have agreed in principle to abandon plans for a £25 million temporary arena in Greenwich.
The Mayor said: "I thank the two federations for understanding our concerns to save money in these tough economic times."
If finally rubber-stamped by the sports organisations, athletes will be offered hotels within walking distance of Wembley to avoid lengthy trips from the Olympic Village in east London.
The agreement was revealed by Denis Oswald, chairman of the IOC's co-ordination commission, at the end of a two-day inspection of London's preparations.
The Badminton World Federation's council is due to meet in Bali today to discuss the issue.
It had been suggested that London was reneging on a promise that athletes would "compete and not commute", but Mr Oswald said the global financial crisis had caused exceptional circumstances.
