January has long been regarded as a difficult time to sign players. A number of managers try to avoid major surgery in the window, while others will only top their squad up with one or two names.
But sometimes teams are able to turn the winter window into a successful one. Title challenges, Champions League pushes and relegation battles have been defined by one correct signature in January.
Sportsmail has put together a guide to the best January acquisitions since the winter window came about.
10.