Wigan may not be able to start the new season if the club is not sold by 31 August, say the Latics' administrators.
Four parties are in talks but administrators say if a deal is not completed it would leave them responsible for the team and the fulfilment of fixtures.
In a statement they said "they do not wish to commit to something we cannot see through" if the club is not sold.
The English Football League season is due to begin on Saturday, 12 September.
Despite the ultimatum, the administrators say they are optimistic a deal can be done.
"We are still hopeful that one of the bidders will be in a position to sign the contract as set out," they said.
"If the contract is not signed [by 31 August], we will have to reconsider the position on the basis that the new season starts a week later."
Wigan were officially relegated last week after they lost an appeal against a 12-point deduction for going into administration.
The Latics appealed against the punishment on the grounds of 'force majeure' however an independent arbitration panel ruled against them.
The club has also confirmed wages for all staff and the playing squad have been paid in full up to 31 July.
Wigan's supporters' club has advanced the Latics the funds needed to buy next season's first-team kit.
Meanwhile, Chey Dunkley became the latest Wigan player to leave following their relegation after he joined Sheffield Wednesday.
Earlier on Thursday, Kieffer Moore joined Cardiff City as players continue to be sold as the club looks to stabilise its finances prior to a sale.