Those unlucky enough to have missed out on London 2012 Olympics tickets twice may discover their fortunes have changed after organisers announced they will be given first bite at the remaining 900,000 seats on Friday morning.
Around 20,000 people are eligible for the special 31-hour sales window from 11am and will have a chance to buy four each of the thousands of tickets available for blue riband events such as the men's 100m final and the opening and closing ceremonies.
From Sunday, the 1million others who were unsuccessful in the first ticket ballot in March last year and did not try to buy any in the second sales window will then have a five-day sales period to buy remaining tickets on a first-come, first-served basis.
Tickets for different sports will go on sale each day, in an attempt to minimise the difficulties that have been experienced by the Ticketmaster system in previous sales windows.
Ticketmaster's managing director Chris Edmonds warned however that it could take 20 minutes of 'queuing' and that many fans would be unsuccessful in buying tickets for the event they wanted.
He said: "Hundreds of thousands of people could be hitting the website. There is potentially going to be some slowing up within the ticketing process, consistent with putting on sale an event of a major artist like Madonna or Lady Gaga.
"You will have the scenario where you can have four tickets left for a session and 1,000 people trying to get them. The reality is that only one can be successful and the other 999 will get a message saying they have been unsuccessful."
The system means those who had initially been unlucky twice over will now get the chance to cherry-pick from the most prestigious events.
London 2012 chairman Sebastian Coe said: "We know thousands of sports fans were disappointed when they missed out in the initial sales period because of the massive demand for tickets. We promised we would prioritise these fans when we released the contingency tickets, which is exactly what we are doing."
The system will, however, penalise those who missed out in the first round but were successful in eventually buying any tickets whatsoever, including football tickets in different parts of Britain: they will have no access to the 900,000 tickets.
London 2012 chief executive Paul Deighton accepted that situation was not ideal in those cases but that it was "impossible" for the system to distinguish between tickets for different sports.
For the first time, 70,000 Olympic Park tickets will be sold which will allow access to the Park to watch sport on the big screens but not to any actual sessions, costing £10 or £5 for those aged 16 or under or 60 or over.
Deighton announced that there will be 5,000 tickets for the men's 100 metres final, 5,000 for the opening ceremony and 6,000 for the closing ceremony.
He expects all the ceremonies and athletics sessions to sell out on Friday to the 20,000 people who get the first chance to buy tickets.
The remaining tickets for the Paralympics will go on sale from 11am on May 21 - exactly 100 days before the opening ceremony of the Paralympic Games.
Organisers also confirmed 'babes in arms', aged 12 months or under, will be permitted access to all London 2012 venues without a ticket except for Wembley Stadium, St James' Park, Old Trafford and North Greenwich Arena, where existing licensing agreements mean that all spectators require tickets regardless of age.
Babies "must be securely strapped to their parent or carer by way of a baby carrier, sling, papoose or similar".
There will be a final sale of around 150,000 tickets nearer the Games that will go on sale once the layout of the venues is finalised.
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