#1 Gerard Pique - 2008
The first place on this list could only go to Gerard Piqué, for the simple fact that he was an absolute bargain. £5 million for one of the world's finest defenders is a genius piece of business.
Piqué is actually a La Masia graduate, but he joined Manchester United in 2004. He didn't get many opportunities in the first team at United, but Guardiola saw his potential and signed him.
The rest is history. Piqué has now formed probably the best centre back pairing with Samuel Umtiti and is an indisputable starter at Barca. A world champion with Spain and one of the world's greatest center backs.
He still remains the greatest signing made by Guardiola in his time at the club, and it is very hard to imagine any future signing better than this one.
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