4. Petr Cech
Chelsea's £7m purchase of Petr Cech from Rennes in 2004 must surely go down as one of the best deals of the decade.
The 31-year-old has been exceptionally consistent since arriving at Stamford Bridge - and his performances have helped the Blues win three Premier League titles, four FA Cups, two League Cups and a Champions League over the last nine years.
His story is made all the more remarkable by the fact he returned from a depressed skull fracture in January 2007.