Graeme Souness believes Philippe Coutinho inadvertently played a crucial role in Liverpool's Premier League title success.
The Reds sold Coutinho to Barcelona in 2018, making £142million for the Brazilian and preventing the Catalan club from buying anymore of their players for two years.
At the time, the transfer appeared disastrous for Liverpool, who were parting company with their best player. But the Reds reinvested the money brilliantly.
The signings of £75m defender Virgil van Dijk and £67m goalkeeper Alisson proved to be the final pieces of the jigsaw puzzle, leading the club to European and domestic success.
And Liverpool legend Souness reckons, with the benefit of hindsight, that selling Coutinho was the club's greatest ever bit of business.
"The secret of consistency is driven by the manager," Souness told Sky Sports.
"I never get fed up of saying this, you can't be successful unless you have good senior pros. I think the senior pros are driving that consistency.
"'We can't drop our standards', as well as the manager. In terms of recruitment, it's still the single biggest thing you have to get right at a football club.
"If you're recruiting well, you're getting leaders, you're getting player who are talented, you get the right players in your club.
"That self-perpetuates itself to the marvellous team we have here. I seem to finish every sentence with 'this team isn't going anywhere, this team won't be beaten for a while'.
"When you say what's the most important signing, I think you can look back to when Liverpool went from a good team to a great team.
"They sold Coutinho and got £160m or whatever it was, they got Alisson and they got Van Dijk and still had change left over. That's got to be the best business this club has ever done."
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