The deal sees the Dutchman become the most expensive defender in transfer history and it could spark a number of rival clubs into action this winter.
Usually, the January window is a quiet time for the traditional top six, but that could change this year.
Fans in the Kop will be hoping they don’t have to watch Philippe Coutinho leave Anfield until at least the summer.
Ahead of the window swinging open, how well do you know Liverpool’s business when it comes to the January period.
We challenge you to name every Reds’ January deal since 2008, either a permanent deal or a player joining on loan.
Take our quiz and share your score with us on Facebook or Twitter.