Derby County have entered administration and been deducted 12 points by the English Football League.
The Championship club announced their intention to call in administrators on Friday, with owner Mel Morris saying the coronavirus pandemic had cost them about £20m in lost revenue.
Morris has spent the past two days talking to players and staff, whose jobs are now uncertain.
Wayne Rooney's Rams drop to the foot of the table, on minus two points.
Andrew Hosking, Carl Jackson and Andrew Andronikou, managing directors at business advisory firm Quantuma, have been appointed joint administrators.
"We are in the early stages of assessing the options available to the club and would invite any interested parties to come forward," said Hosking.
"Our immediate objectives are to ensure the club completes all its fixtures in the Championship this season and finding interested parties to safeguard the club and its employees."
The EFL said it had already had "constructive discussions" with Quantuma and would remain in "regular dialogue" about the situation.
EFL chief executive Trevor Birch said: "I appreciate that this is a challenging and concerning period for everyone associated with the club, particularly the staff and supporters, and it is our intention to work proactively with the administrators and all relevant parties with the objective of securing a long-term and viable future for Derby County."
Club lost Morris 'in excess of £200m'
Morris became Derby's sole owner in 2015 but has actively been looking to sell since June 2019 following their Championship play-off final defeat by Aston Villa under Frank Lampard. Morris says the club has lost him "in excess of £200m" to date.
A first takeover deal is said to have collapsed in the aftermath of an EFL charge in January 2020 relating to the sale of Derby's Pride Park to Morris for £80m, despite it previously being listed as worth £41m.
The stadium sale allowed the club to post a pre-tax profit of £14.6m in 2017-18 and therefore meet the EFL's spending rules.
The charge was dismissed in August 2020 but the Rams face a possible separate points deduction, speculated to be nine points, over their accounting policies - with no decision yet made on the punishment.
'Serious enquiries' for the Rams
Derby have been under a transfer embargo since before the summer window opened, meaning the Rams have only been allowed to sign free agents with strict conditions on salaries.
Morris told BBC Radio Derby on Sunday that there had been "something in the region" of 15 enquiries for the club over the weekend, two or three of which he said were "very serious".
On the pitch, Derby had been 12th in the Championship under the management of England's record goalscorer Rooney, who has been in permanent charge since he officially retired as a player in January.
However the automatic penalty for going into administration will put the Rams six points adrift of second-bottom Nottingham Forest, their East Midlands rivals.
Derby situation echoes 1984 crisis
Derby were also in serious financial trouble in 1984 - less than a decade after the second of their Division One title wins - when former chairman Stuart Webb was a member of the board, and he criticised Morris' decision to "walk away" from the current situation.
"We worked relentlessly to keep the club alive which in the end we were able to do," Webb told BBC Radio Derby.
"We all worked together to keep it going but at this point it looks as though it's come to the end, and that really is worrying for everyone. Once the administrator is appointed, then we'll really find out what the extent of the problems is and how it's going to be dealt with, and that's not going to be pleasant."
Under Morris, the only other board members were company secretary Stephen Pearce and former Derby captain and manager Roy McFarland.
Webb added: "Mel Morris came in as a highly successful businessman but was clueless about the running of a football club. You need experienced people who can manage a huge business. You need to get the club on an even footing and if you go deeper down into a financial mire, take advice but don't walk away."
Derby are now facing the prospect of relegation to League One and insolvency expert, and former Leeds United chairman, Gerald Krasner, told BBC Derby: "If they don't sell the club, then it's liquidation and expulsion like Bury and clubs before them. That would be a great shame with a history like Derby's."
'Rooney is the man to lead the battle'
Ed Dawes, Derby County commentator for BBC Radio Derby:
Disbelief, tears, anger and frustration. The emotions of supporters of Derby County since Friday evening.
Saturday's win over Stoke City and the atmosphere at Pride Park was a stopgap to the eventual reality that the Rams would be placed bottom of the Championship, which is now where they are.
Questions surrounding chairman Mel Morris' 'cut and run', as it has been called by many supporters, still need to be answered and perhaps we will only find out now what state the football club is in.
A debt of more than £50m is not going to be turned around by the likes of a Lionel Pickering, the Rams' former chairman who spent his entire local newspaper fortune on the club. It will need to be a global multi-millionaire who can run a business and a football club, but be happy to wipe out the debt owed in one fell swoop.
The worry for supporters is not only the immediate 12-point deduction, it is the next move by the EFL regarding the unsubmitted accounts. Morris told me exclusively on Sunday that there is a failure of profit and sustainability rules in the recalculated documents following the amortisation saga, which in turn could lead to more points being taken off.
The one thing that is obvious around Derby right now is the togetherness of the fans and support for Wayne Rooney. Every battle needs a leader and Rooney is that man. He is unlikely to keep Derby in the Championship, but he told me on Saturday he is committed to the club and to navigate this journey. Whether that will be up to him and his price, rather than his ability, we will have to wait.
The club nearly went bust in 1984 in their centenary season, while the 2021-22 season marks 50 years since Brian Clough's side won their first old First Division title. A penny for his thoughts.
- Who is Marvel's latest superhero? Movies With Ali Plumb reveals all about Shang-Chi
- How to eat well at university: BBC Food has top tips for budgeting, planning and keeping things tasty