Deighton said the ticketing system had so far coped well with the numbers of people applying, with more than 2.5 million having signed up before sales began on March 15.
"The system has actually worked faultlessly, and with a process of this scale and complexity that is extraordinary," he told PA.
"Even though I am expecting we will have significant demand, we are confident with the way the system is working and that it can support anything that the ticket-buying world can throw at us.
"There will be a number of tickets left over. It was always the plan."
Two million tickets for the 2012 Paralympics also in London will become available in a similar ballot starting on September 9 and finishing that month.
computer smsSan Francisco Movers