Liverpool's sporting director Michael Edwards struck an agreement with Barcelona during the sale of Philippe Coutinho, forbidding them from buying a Reds player until 2020.
The Brazilian midfielder joined the Catalan side at the start of this year for a staggering £142 million, following the likes of Luis Suarez and, previously, Javier Mascherano.
As part of the agreement, Edwards ensured that the Spanish giants would be unable to buy another Liverpool player until 2020, according to the Telegraph‘s Chris Bascombe.
It emerged on Wednesday that should Barcelona want to prise another Reds star away from Anfield, they must pay a premium of €100 million (£89m) on top of any transfer fee.
It is said that Liverpool had a feeling of “distaste” with how Barcelona attempted to turn Coutinho's head since the previous summer and were adamant on the clause be inserted.
With Barcelona being one of the only clubs able to lure Liverpool's players, the deal negotiated by Edwards has been applauded by Liverpool supporters.
Liverpool forwards Mohamed Salah and Roberto Firmino have both been linked with Barcelona in recent months, however the clause all but ensures that they would be unable to afford the significant transfer fees.
Liverpool had written to Barcelona in the summer of 2017, warning that should they continue to aggressively pursue Coutinho, they would be forced to report the Spanish side to FIFA for illegal transfer activity.
However, Barcelona sponsors Nike provoked the Reds further by announcing his arrival weeks before an agreement was reached.
The move did finally occur with Coutinho's persistent wish to leave Anfield, however the Reds made sure they made a significant profit on the former Inter Milan man, who joined Liverpool for £8.5million in January 2013.