#3 Petr Cech (£11.7m from Rennes)
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This was probably Mourinho's best signing in terms of value for money. Petr Cech solved Chelsea's goalkeeping problem immediately and provided the foundation that Mourinho's side needed to win back-to-back Premier League in 2005 and 2006.
Prior to Cech's arrival, Carlo Cudicini was destined to be Ed de Goey's successor between the posts. However, the Italian continuously made errors that were costly at times and a new solution had to be found.
The goalkeeping position is essential for any team that wants to mount a serious title bid and Petr Cech proved to be fantastic for Chelsea for over a decade. Had Thibaut Courtois not impressed the way he did on loan at Atletico Madrid, we would probably still be seeing this man between the posts at Stamford Bridge.
The fact that Cech is still playing at Arsenal at the age of 35 is a testament to his outstanding abilities and we have Mourinho to thank for discovering one of the best goalkeepers of the Premier League era.