Liverpool's signing of Virgil van Dijk has arguably been their most important piece of business this millennium.
The Dutchman has transformed the Reds from an attack-heavy force into a well-balanced, efficient machine that looks capable of winning every major trophy.
He may have cost £75m - a fee that looked astronomical at the time - but his price tag now looks like a real bargain.
Liverpool currently sit top of the Premier League having conceded just 13 goals all season, with Van Dijk scooping the PFA Player of the Month for December.
He was the first defender in six years to lift the award.
The deal for Van Dijk was one steeped in controversy. Liverpool were forced to apologise to Southampton in the summer of 2017 after allegedly 'tapping up' the Dutchman.
Then just before the opening of the 2018 January window, Liverpool announced a deal had been sealed for Van Dijk out of nowhere.
And it turns out club captain Jordan Henderson played a pivotal role in Liverpool's continued pursuit of him.
Melissa Reddy revealed in her detailed piece about Liverpool's rise to the top about how the midfielder - who shares the same agent - was constantly on recruitment's case to sign Van Dijk.
She wrote, per JOE: "Jordan Henderson, whose role in helping Liverpool land the world’s most expensive defender has not been given the consideration it deserves - they share an agent and the captain kept on at recruitment to do everything possible to secure Van Dijk - mentioned that turning around in the tunnel and seeing those two [Van Dijk & Alisson] was like a victory before kick-off."
Henderson is often a divisive figure among the Liverpool fan base, but there will be no criticism aimed at him for his desire to bring Van Dijk to Anfield.
With Alisson, Van Dijk, Joe Gomez and Andrew Robertson at the back, Jurgen Klopp's side have a backline that will be feared across Europe for years to come.