Sokratis Papastathopoulos born 9 June 1988 in Kalamata. Sokratis is a Greek international football player currently playing as a defender for A.C. Milan in the Serie A.Papastathopoulos joined AEK Athens from Apollon Petalidiou for €30K On October 26, 2005 he made his debut for AEK Athens in a Greek Cup match against PAS Giannina scoring in the 7th minute of the game leading AEK Athens to a 3–0 win.On January 2006 he was loaned to Greek Second Division club Niki Volou for 6 months in order to gain first team football and gather valuable experience. He made a total of 15 appearances for Niki Volou.
During the 2006–2007 Greek Super League, Papastathopoulos managed to make 14 appearances whilst competing against the likes of Bruno Cirillo, Traianos Dellas and Vangelis Moras. In AEK Athens’ UEFA Champions League 2006-2007 campaign, Papastathopoulos managed to play in 3 out of the 6 group games. In these 3 games AEK Athens managed 1 win (the famous 1–0 victory over A.C. Milan), 1 draw (the 2–2 away draw with R.S.C. Anderlecht) and one loss (the 3–1 away defeat to Lille OSC). During the 2007–2008 Greek Super League, he has been a mainstay in AEK’s defence, keeping out competition from Geraldo Alves.On August 1, 2008, Papastathopoulos agreed to transfer to Genoa, a Serie A team, for a fee of €4 million . He made his debut for Genoa on 27 September 2008 against Fiorentina, followed by a start against Ravenna Calcio in the Coppa Italia a few days later. His first goal for Genoa came on the 5 October 2008 at home against S.S.C. Napoli. Genoa won the game 3–2, but Papastathopoulos was sent off in the 89th minute  During the 2009–2010 season he has managed to play in most games and has become somewhat of a fan favorite.
On 20 July 2010, it was confirmed in a naote in AC Milan’s Website that Papastathopoulos has joined the team , after Genoa and Milan had reached an agreement to transfer Papastathopoulos to the club in exchange for Gianmarco Zigoni, Nnamdi Oduamadi and Rodney Strasser in co-ownership deal, plus an undisclosed fee.He was called up on February 1, 2008 and made his debut on February 5, 2008 in the 1–0 friendly victory against Czech Republic. The Greece squad for Euro 2008 was announced by Otto Rehhagel on May 27, 2008, and Papastathopoulos was the unfortunate player to be cut from the provisional squad of 24 to the final 23-man selection.
He was recalled for a friendly against Slovakia on 10 August 2008, about a month after Euro 2008. From then, he has been a regular squad member for Greece. He featured in 4
2010 FIFA World Cup qualifying matches and helped his country to qualify for the final tournament.