Bolton Wanderers have confirmed they have received a winding-up petition from Her Majesty's Revenue and Customs for about £600,000 in unpaid taxes.
The Championship's bottom club are currently £172.9m in debt.
Despite Bolton asking for more time to raise the money or sell the club, HMRC decided to serve the petition.
"Quite clearly the club remains in a critical financial position," said Trevor Birch, who is acting as financial advisor for Bolton.
"We will continue to try and finalise a sale or alternatively raise some short-term funds needed to give the club breathing space and time in which to consider its options."
The threat of administration
There are understood to be four parties interested in taking over the club.
If Bolton enter administration they will automatically be deducted 12 points.
"I think Trevor has a few plans in place to avoid that scenario," manager Neil Lennon told BBC Radio Manchester.
"He's confident he can avoid that because that would mean we'd be a League One team and we'd just be fulfilling fixtures for the rest of the season."
Will Bolton be forced to sell players?
Former Bolton striker Dean Holdsworth is leading one of the parties interested in a takeover, while former Trotters midfielder Stelios Giannakopoulos is part of another.
"What we need is someone to come up with the money and help the club out and just get us through a difficult period until January," added 44-year-old Lennon.
"However, what we may have to do in January is sell some assets in terms of the football side. That could be a realistic proposition.
"If that means getting the club through stormy waters then that's what we'll have to do.
"It's not ideal for a manager, but the club's future is the priority rather than the present."