The Raine Group have told the three remaining parties in the race to buy Chelsea that they must prove they will remain at the club until at least 2032.
Current owner Roman Abramovich is keen to ensure Chelsea is passed to the most suitable owner and is seeking assurances from the three remaining bidders - Todd Boehly, Sir Martin Broughton and Stephen Pagliuca.
One of those assurances, according to Sky News, is that they will not sell their controlling stake in the club until at least 2032 - an unprecedented request when it comes to an auction to buy a football club.
It is understood that a guarantee to remain at the club for ten years would be written into the purchasing contract, making it enforceable by law instead of just a verbal agreement.
The response to that request from Boehly and Broughton is not yet clear, but the consortium led by Pagliuca has already vowed to remain in control at Stamford Bridge for as long as physically possible.
Larry Tanenbaum, who is part of the Pagliuca bid, said: "My goal, and that of Steve, would be to own Chelsea for decades to come."
Interestingly, there have been reports that Pagliuca's bid could be eliminated from the race, although the Telegraph state that the Boston Celtics owner is mystified by such claims and believes they could be a 'dirty trick' by one of the other prospective buyers.