The club announced the signing of Cesar Azpilicueta on 24 August 2012.
The 22-year-old right-back, who represented Spain at the London Olympics, arrived at Stamford Bridge following a two-year spell in France's Ligue 1 with Marseille.
Born on 28 August 1989 in Pamplona, Navarre, he began his career at the academy of his hometown club, Osasuna.
Having started out as an attacking midfielder, Azpilicueta is comfortable in possession with a good range of passing.
Having come through the ranks at Osasuna, Azpilicueta was handed his La Liga debut on 8 April 2007 against Real Madrid at the Bernabeu.
The following season, with Osasuna depleted by injuries, the youngster featured regularly and cemented his place in the team at right-back with a string of impressive displays, while the 2008/09 campaign saw him miss only two games.
In June 2010, Azpilicueta made the switch from Spain to France, signing a four-year deal with Marseille.
The youngster, however, endured a difficult opening to his career at the club suffering a knee injury which ruled him out for his first season.
Following the disappointment of the previous campaign, the 2011/12 season - with both the European Championships and Olympics on the horizon - was always going to be a big one for the young Spaniard.
He flourished, performing consistently well and catching the eye as Marseille reached the Champions League quarter-finals, eventually eliminated by beaten finalists Bayern Munich.
At international level, he has represented Spain since earning a call-up to the Under 16s in 2005, and was part of the Under 19 side which won the European Championships back in 2007, as well as the Under 21s who tasted success in the same competition in 2011.
He joined fellow countrymen Juan Mata, Oriol Romeu and Fernando Torres at the club.