Liverpool are reportedly still owed £12.3m from Barcelona for the signing of Philippe Coutinho.
The Brazilian left Liverpool to join Barcelona for £142m in 2018, with the deal also including £4.4m for every 15 appearances the player made for the club.
Despite registering 25 goals and 14 assists in 106 appearances, Coutinho struggled in his time with Barcelona, which included loan spells with Bayern Munich and Aston Villa.
While the 30-year-old joined Villa on a permanent deal in the summer, according to the Daily Express, Liverpool are still owed £12.3m by the Catalan giants.
The report indicates that if the Reds receive those funds in the near future, then they could be put to use in the January transfer window.
Barcelona are also still to pay the full transfer fee to Juventus for Miralem Pjanic, while Manchester City are also owed £46m for Ferran Torres.