Sokratis Papastathopoulos (; born 7 June 1988), commonly known mononymously as Sokratis, is a Greek professional footballer who plays as a centre-back for Super League club Olympiacos. Club career AEK Athens Papastathopoulos joined AEK Athens from Apollon Petalidiou after being scouted by Toni Savevski. On 26 October 2005, he made his debut for AEK in a Greek Cup match against PAS Giannina, scoring in the seventh minute of the game to help lead AEK to a 3–0 win. In January 2006, he was loaned to Beta Ethniki club Niki Volou for six months to gain first-team football experience. He made 15 appearances for Niki Volou. During the 2006–07 Super League Greece, Papastathopoulos managed to make 14 appearances whilst competing against the likes of Bruno Cirillo, Traianos Dellas and Vangelis Moras. In AEK Athens' 2006–07 UEFA Champions League campaign, Papastathopoulos managed to play in three out of six group games. In these three games, AEK managed one win (the famous 1–0 victory over A.C. Milan, where he man-marked Filippo Inzaghi), one draw (the 2–2 away draw with Anderlecht) and one loss (the 3–1 away defeat to Lille). During the 2007–08 Super League Greece, he was a mainstay in AEK's defence, keeping out competition from Geraldo Alves. He also played in the 2007–08 Champions League campaign, and in a Super League match, he became AEK's youngest-ever captain (age 19) in a game against Athens' local rival Panathinaikos in 2008. Genoa On 1 August 2008, Papastathopoulos agreed to transfer to Genoa of the Italian Serie A for an undisclosed fee. He also played a club friendly against Genoa on the same day. He made his debut for Genoa on 27 September 2008 against Fiorentina, followed by a start against Ravenna in the Coppa Italia a few days later. His first goal for Genoa came on 5 October 2008 at home against Napoli. Genoa won the game 3–2, but Papastathopoulos was sent off in the 89th minute During the 2009–10 season, he managed to play in most games and gained a following. A.C. Milan On 20 July 2010, the A.C. Milan website confirmed that Papastathopoulos had joined the team, after Genoa and Milan reached an agreement to transfer Papastathopoulos to the club for €14 million, with the following payment schedule: Gianmarco Zigoni (half of his registration rights, valued at €3.75 million), Nnamdi Oduamadi (half of his rights, valued at €3.5 million) and Rodney Strasser