The Philippe Coutinho to Barcelona transfer saga dominated the summer 2017 and January 2018 windows.
Liverpool's Brazilian magician was seen as the perfect man to succeed Neymar in Catalonia after his £198m move to Paris Saint-Germain.
It was a summer of constant speculation, which eventually saw Coutinho stay on Merseyside and Barca sign Ousmane Dembele from Borussia Dortmund.
However, the La Liga giants would get their man a few months later, with Coutinho joining the Blaugrana in a £142m deal in January.
Jurgen Klopp's side reluctantly agreed to the sale as there was no point keeping a player with his head elsewhere.
Coutinho's transfer fee also allowed the German manager to rebuild his squad in the last transfer window.
The Brazilian was not the first to swap Merseyside for Catalonia, with Luis Suarez doing the exact same back in 2014.
Barca have also been linked with moves for Roberto Firmino and Mohamed Salah in the past.
And it seems Liverpool decided to act when they sold Coutinho to Barca, inserting a clause into the deal that really is quite extraordinary.
As revealed by Times journalist Paul Joyce - the go-to man for Liverpool news - Barca would have to pay an £89m premium on any Reds player up until 2020.
What does that mean? Well, if they were to try and sign Salah, who would be worth around £150m right now, Barca would have to fork out £239m.
The remarkable clause was negotiated by Michael Edwards, who clearly wasn't too pleased with the Blaugrana poaching yet another talismanic figure at Anfield.
It also means that Sadio Mane - who is still yet to sign a new contract with Liverpool - will certainly not be heading to the Nou Camp if he does opt to leave in the near future.
However, the Coutinho clause would play no part in Barca's interest in Alberto Moreno, with the left-back's contract up at the end of the 2018/19 season.