A decision on who will move into the £537 million Olympic Stadium has been postponed from Friday, the Olympic Park Legacy Company have said.
A spokesman said "more time is needed to consider the bids". Barclays Premier League rivals West Ham and Tottenham are in a head-to-head race to move into the stadium in Stratford, east London, after the 2012 Games.
An OPLC spokesman said: "Given the detailed nature of both bids received, we need more time to seek further clarification with both bidders in order to identify a preferred bidder. The stadium is a significant public asset and we have a duty to run a robust process."
An OPLC board meeting on Friday was widely seen as the point when a final decision would be made for the showpiece stadium. The OPLC is in charge of securing an economically viable future for the Olympic Park.
Final submissions were made by the rival bidding teams last Friday.
The spokesman added: "Securing the most appropriate solution for the stadium is vital to our long-term aspirations for the future Queen Elizabeth Olympic Park and the wider regeneration of the area.
"In addition to the two shortlisted bids, the Legacy Company also has the option of the original plan to convert the Olympic Stadium to a 25,000 seats, mixed-use venue. In going to market, the Legacy Company's aim was to consider options which would enhance and build on that plan."
West Ham, in a joint bid with Newham Council, want to create a 60,000-capacity arena for football, athletics, concerts and community use.
Tottenham, in a joint bid with sports and entertainment giant AEG, have pledged to create an athletics legacy elsewhere and contribute to the refurbishment of the National Sports Centre at Crystal Palace.
An athletics legacy was one of the key promises that London 2012 made to the International Olympic Committee when it won the right to stage the Games.
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