European football's governing body UEFA has warned Manchester City it may reopen its 2014 Financial Fair Play (FFP) investigation into the club.
City outplayed local rivals Manchester United on Sunday and are two points clear at the top of the Premier League - but things may not be so healthy off the pitch.
Citing documents and emails provided by the whistle-blowing platform Football Leaks, German magazine Der Spiegel has published a series of articles over the last 10 days which have accused City's Abu Dhabi owners of trying to get around European football's FFP rules.
Some at UEFA believed that to be the case in 2014, too, and the club was punished - but Der Spiegel claims the governing body was unaware of some of the details.
City have repeatedly described Der Spiegel's reports as the product of a "clear and organised" attempt to tarnish their reputation, while UEFA's initial response was to say it could not comment because of "confidentiality obligations".
But with Der Spiegel's specific allegations remaining unchallenged, UEFA has finally indicated it has the stomach for a fight.
In a statement, UEFA said it makes an annual assessment of all clubs against FFP's break-even requirements on a rolling three-year basis, and this assessment depends on "fair and accurate" information provided by the clubs, as well as "compliance checks and analysis undertaken by UEFA".
"If new information comes to light that may be material to this assessment, UEFA will use that to challenge the figures and will seek explanation, clarification or rebuttal from the club concerned," it continued.
"Should new information suggest that previously-concluded cases have been abused, those cases may be capable of being reopened as determined on a case-by-case basis."
UEFA also defended the FFP system, saying it had helped clubs across Europe go from a cumulative debt of £1.5billion in 2011 to more than £500million in profits last year.
"Without question, (FFP) has been a success for the game across Europe," it added.
Manchester City have told UEFA chiefs that wealthy benefactors should not be penalised under financial fair play rules for investing heavily in clubs.
City and Paris St Germain were each fined £49million for FFP rule breaches last season - and both clubs sent senior figures to a meeting chaired by UEFA president Michel Platini on Monday in Nyon, Switzerland, to discuss any changes to the rules.
City chief executive Ferran Soriano attended the meeting, as did PSG chairman Nasser Al-Khelaifi and it is understood both stressed their belief that sustainable investment should be permitted.
No decisions were taken at the meeting, which also discussed whether large debts carried by clubs such as Manchester United and Real Madrid should also be tackled more strongly by FFP rules. Currently, only the interest on those debts is viewed as part of the FFP calculation