Interesting deals are made during transfers and so many hidden clauses are included in deals and it is not shocking that Liverpool and Barcelona had one in the sale of Philippe Coutinho.
Back in 2018, the Reds could do nothing to stop the sale of their Brazilian star to the Catalan giants, but they did something to make sure none of their top players leave for the Spanish side for a while.
In recent years, Liverpool had sold Javier Mascherano and Luis Suarez to Barca, but they were not going to make another top sale anytime soon.
So, they tried to make the Coutinho deal a little bit complicated.
First, the Reds demanded a transfer fee of £142million.
This entire figure wasn't paid upfront, with Liverpool initially banking £105million, before receiving the rest in installments after certain milestones were triggered.
From this money, they bought Virgil van Dijk and Alisson who as we all know, have done so well for the club up to date.
But the greatest thing from the deal - from Liverpool's perspective - was a secret clause the Reds insisted upon.
Now, in a bid to stop Barcelona poaching more of their players, Liverpool struck a deal with the Catalan's that would result in them having to pay an additional £89million premium on any Liverpool star they wished to purchase before 2020.
This worked a treat for the Reds, with Barcelona keeping their distances and allowing Klopp the time to keep his team intact and turn them into Champions League and then Premier League winners.
But, this deal has now expired. What happens now?
Well, for one, now that Barcelona no longer has to pay a premium to sign a Liverpool player, Anfield is back on the Catalan club's shopping list.
But, will this happen with how the Reds are flying high and Barca is somewhat struggling?
There is more to follow! Maybe.