It's safe to say Juan Mata's sensational switch to Manchester United is going to take some beating this month.
Though many had expected the Spaniard to depart Stamford Bridge eventually, few would have anticipated a move mid-way through a season, made even more eyebrow-raising due to the club he transferred to.
If nothing else it stands to prove that the winter transfer window is becoming an increasingly important period when it comes to teams adding vital components to their squads in a bid to change their fortunes from January onwards.
With this in mind we cast our eyes back across the last decade to see who were the best January buys of the ten years just gone.
They may not have cost much, may not have made an immediate impression and may have even originally been met with some disdain but fear not! All of these guys went on to, or are going to, achieve great things...
*DISCLAIMER: We've picked our best based purely on how well the player has taken to his new club, not taking valuation, cost or subsequent decline into account.