Stadium Australia's capacity has been reduced to 69,000 for the third and final Test between the Lions and Australia in Sydney.
And Australian rugby chiefs fear less than 4,000 tickets will go on public sale for the match on July 14th as a result.
A rugby union world record crowd of 109,000 watched Australia take on New Zealand in last year's Bledisloe Cup match at the stadium but a post-Olympics redevelopment programme has meant vastly reduced seating numbers.
The capacity will be increased to 85,000 though when Australia tackle the All Blacks on September 1st.
The Australian Rugby Union had lobbied government officials to delay any stadium revamp until after World Cup 2003 - which Australia will host - yet found little support for their proposals.
But there is no danger of the third Lions Test being switched as the ARU will honour their existing Stadium Australia contract.
"This Test is a blockbuster event which could have filled Stadium Australia three times over," said ARU managing director John O'Neill.
"Now we have the prospect of offering very few tickets for public sale because of the capacity issue.
"Through a combination of stadium memberships, allocations to rugby clubs, in-bound tourists on travel packages, our own memberships and other legal and contractual obligations, the pool of tickets available for public sale is minimal.
"One of the conditions of getting the Lions out here was guaranteeing a further 8,000 tickets for travel packages so that Lions supporters could follow the tour and it all eats into our ability to put tickets on public sale," he added.
The Test series kicks off at The Gabba in Brisbane on June 30th followed by a showdown at Melbourne's new Colonial Stadium seven days later.
PA