Anyone wanting tickets for the Olympics can now register online.
Signing up - at www.tickets.london2012.com - does not guarantee a ticket but it is a short cut to the public ballot for 75% of the tickets. They go on sale in spring next year.
Sports fans who register will have their interest noted and get updates on test events, major competitions and when tickets become available.
Another 800,000 tickets - up from 9.2 million to 10 million - will now available for the Games because of modelling work at the 2012 venues.
Originally there were to be 9.2 million tickets for the London Games - 7.7 million for the Olympics and 1.5 million for the Paralympic Games.
Now there will be eight million tickets sold for the Olympics and two million for the Paralympics.
Making the announcement in Trafalgar Square, London 2012 chief executive Paul Deighton said: "Anyone who signs up will be in pole position for our ballot of tickets.
"The aim is to make the process as easy as possible and get people thinking about which sports they want to watch from all the different Olympic and Paralympic sports.
"We expect people to be more interested in tickets for some events than others. There is no fairer way for people to get in line for those tickets than by public ballot."
