Manchester City confirmed Friday they had launched an appeal against a damning judgement that found the club guilty of all charges related to serious breaches of the Premier League’s financial rules.
An independent commission delivered its findings on the Abu Dhabi-backed club earlier this week and City had until Friday to appeal.
The Premier League leaders announced shortly before midday (1000 GMT) they had done so.
No sanction has yet been decided upon but City could face substantial points deductions, a fine or even expulsion from the top division.
The 10-time English champions, who continue to deny any wrongdoing, said Friday they had lodged a "comprehensive appeal" the previous evening.
"The club's firm position is that, on multiple grounds, the opinion contains clear material errors, of law, principle and fact and is unsafe," City said in a statement.
"The club is innocent of the accusations made by the Premier League and a comprehensive body of irrefutable evidence exists in support of all of its positions, relating to this case.
"We will continue to respect due process and are necessarily restricted in what we can say further until all proceedings are complete."
Earlier on Friday, the English Football Association broke its silence on the case, saying that the commission's decision "has significant implications for the integrity of the game".
"We are carefully considering the decision and its implications and will take action where appropriate," the national governing body said in a statement.
- Sponsorship deals -
It has been widely reported that City will claim that key sponsorship deals were funded by the Abu Dhabi government, rather than the club's owners, as part of their appeal.
State-owned bodies are not banned from sponsoring clubs under Premier League rules.
The commission found City had arranged "sham" commercial deals with a number of its sponsors that were part of a "disguised funding scheme".
It said those companies were only required to pay a portion of the relevant sponsorship fees, with the remainder funded by club owners Abu Dhabi United Group.
Private investment company ADUG, owned by Sheikh Mansour bin Zayed al-Nahyan, bought City in 2008 and has transformed the club from also-rans into a dominant force.
Sheikh Mansour is also vice-president, deputy prime minister and chairman of the Presidential Court of the United Arab Emirates.
The commission said the deals artificially inflated revenues and reduced costs by more than £900 million ($1.2 billion) between 2009 and 2018, a period in which they won three Premier League titles and other silverware.
It found the club had concealed the true state of its finances, saying City were "significantly in breach of both the Premier League's and UEFA's spending limits".
Downing Street said on Thursday that the super-club was not "above the rules" following criticism of British Prime Minister Andy Burnham over the case.
"As the prime minister made clear, the initial judgement is serious and there can't be any suggestion that anyone is above the rules," a spokesperson said.
Burnham, the former mayor of Greater Manchester, told the BBC on Wednesday that he did not want to see the club's Emirati owners walk away as a result of the case.
City could face relegation given the sheer scale of the case and there is even speculation that they could be stripped of their titles.
The club could also face a flood of compensation claims from rivals.
UAE airline Etihad Airways, City's main sponsor, said earlier this week that it was considering legal action against the Premier League.
"Etihad categorically rejects any finding, conclusion or implication that suggests the airline has ever been involved in improper commercial arrangements," an Etihad spokesperson said in a statement.