Back in 2015 Roberto Firmino signed for Liverpool.
The Reds paid £29million for the Brazilian from Hoffenheim and he penned a five-year deal with the Anfield giants.
Football Leaks later revealed that a rather bizarre clause was included in the first contract he signed with Liverpool - one that took aim at Arsenal.
A year before Liverpool signed Firmino, the club parted company with Luis Suarez.
The Uruguayan joined Barcelona from the Reds, but very nearly signed for Arsenal had it not been for some Steven Gerrard intervention and some poor negotiation from the Gunners.
Arsenal infamously upset Liverpool officials during the negotiation period by bidding £40m plus one pound for Suarez, in the belief it would trigger his buy-out clause.
The offer prompted something of a shock reaction from Liverpool owner John W. Henry who tweeted: "What do you think they're smoking over there at the Emirates?"
Not much else came of the offer as Suarez headed to Barcelona, but it seems Liverpool remembered the bid and decided to get some payback a year later in 2015.
According to Football Leaks, written into Firmino's contract was a £89m release clause that could be triggered by any club in the world, except Arsenal.
It seems the move was done in revenge of the bid for Suarez, and prevented the Gunners from entering negotiations with the Reds over signing another one of their forwards.
Firmino has since penned a new deal at Liverpool, suggesting the clause no longer exists.
Will Liverpool win the Premier League again this season? Have your say here.
* Sign up to the Mirror Football email here for the latest news and transfer gossip.
