The striker’s legal team, however, now assert that the “gentleman’s agreement” is invalid as the additional clause was never signed.

As a result, they are claiming Mbappe is owed 55m euros – a sum made up of the final third of his signing-on fee and three months’ worth of wages which were unpaid.

They argue that a written contractual amendment would have had to be signed and submitted to the Ligue de Football Professionnel (LFP) – the governing body for France’s two professional divisions – for the change to be valid, and that no “tangible proof” of an agreement has been presented.

Mbappe brought the case to the LFP, whose disciplinary commission initially issued a non-binding ruling that PSG were to pay the sum.

It later deemed itself to have no jurisdiction over the matter because of an ongoing civil court case, which the player’s team claims was only launched by PSG against the LFP “in order to avoid disciplinary action”.

In February, the French Football Federation (FFF) dismissed Mbappe’s subsequent appeal on the same grounds.

Speaking to BBC Sport, a lawyer with knowledge of PSG’s case explains that the LFP’s decision came from the fact that it could make a judgement based on the original contract – “but what’s being debated is whether it was amended”.

In December, following the LFP’s latest decision, a club spokesperson reiterated that Mbappe had “made clear public and private commitments that the club simply asks to be honoured”, and that PSG remained hopeful of “an amicable solution”.

The club also claimed that Mbappe refused the LFP’s offer for mediation.

Last month, Mbappe’s lawyers held a press conference to announce they had “gone on the attack”, having notably obtained the seizure of the 55m euros from PSG’s accounts through a court decision.

They also indicated that they were filing a complaint claiming PSG put pressure on Mbappe to renew, which the club denies, and that they had sent a letter to the FFF asking them to notify Uefa on the situation.

In a hearing on Monday, after PSG contested the precautionary seizure, the club announced that a counterclaim for 98m euros (£82.6m) in damages would be brought forward as part of their wider case.

In their court submission, the club’s lawyers asserted that the counterclaim was prompted by Mbappe’s “deceptive behaviour during negotiations to revise his contract”.

The striker’s team, meanwhile, reiterated that despite the counterclaim there was “no legal basis for deferring payment of the sum due”.

“The aim is not to recover the 98m euros, but rather to show that if he owes us money, his claim is unfounded,” PSG lawyer Renaud Semerdjian told the AFP.

For the club, the standoff also represents a reversal in the days where player power reigned supreme – the new-look (albeit still as spendthrift) PSG styles itself as a project built around a collective unit rather than individual talents.

Mbappe’s team, meanwhile, claimed in their April press conference that it was PSG who had put him under pressure to re-sign back in 2023 through “scandalous and indecent practices”, and that they would be joining the players’ union in its legal action against the “lofts”.

A decision on the seizing of the club’s accounts is expected on 26 May – the same day as a separate hearing on the wider case, in which the French football authorities initially dismissed Mbappe’s appeals.

While the 26-year-old will have wrapped up his maiden season in Spain the previous evening, Paris St-Germain will be in the midst of a week bookended by the Coupe de France and Champions League finals.

It could be an era-defining week both on and off the pitch for the Parisians.