Fewer than half of the precious seats at London 2012's 100m final have gone to members of the British public, organisers said.
Fans from the host nation will hold just 30,000 of the 80,000 places at the most highly-anticipated event of the Games.
The remaining seats will be taken up by international supporters, with some 20,000 reserved for the "Olympic family" - including officials, sports federations and sponsors - and the media.
London 2012 spokesman Jackie Brock-Doyle said: "We have 60,000 saleable seats in the stadium, 50% of them are going to the British public."
Seating at Olympic venues has become a subject of some contention after rows of empty seats were spotted at "sold-out" events. The issue sparked huge criticism and led organisers to put thousands of unused tickets up for sale online.
Sunday's climax will see the fastest athletes on the planet go head-to-head. But organisers said they could not give a more detailed break-down of how seats for the dramatic showdown have been allocated until after the event.
Away from the stadium, in Stratford, east London, vast numbers of viewers are expected to tune in from across the world to see Jamaican sprinter Usain Bolt, 25, pitted against rivals in what promises to be one of the most talked-about races of the Games.
A London 2012 spokesman said: "There is a difference between ticketed seating and accredited seating.
"Of the 80,000 seats in the stadium, once you take out seats which are used by people with accreditation - and most of these are used by media - there are around 60,000 seats available for us to sell.
"We have always been very open that around 50% of these have been sold to the UK public."