The centre-half started his professional career at Greek side AEK Athens in 2005 before he moved to Serie A side Genoa in 2008.
Sokratis spent two seasons at Genoa before AC Milan signed the Greece international in a complicated co-ownership deal.
Papastathopoulos went out on loan to Werder Bremen for the 2011-12 season before he made his switch permanent at the end of the campaign.
The Greek defender was on the move again in 2013 after he completed a switch to Borussia Dortmund in €9.5m deal.
Sokratis won the German Cup and German Cup during a five-season stint at Dortmund before he completed a £17.7m move to Arsenal in July 2018.
He has scored three times in 79 games for the Greece national team since making his debut in 2008.
• Date of birth: 9 June 1988
• Age: 30 years old
• Place of birth: Kalamata, Greece
• Nationality: Greek
• Height: 186cm / 6ft 1 ins
• Weight: 82kg / 181 lbs
• Wages: £108,000 a week
• Transfer value: £17.7 million
The commanding defender was born in Kalamata, Greece,
Sokratis came through the youth ranks at Apollon Petalidiou before joining AEK Athens as a 17-year-old in 2005.
He made his debut in AEK’s 3-0 win over PAS Giannina and scored the first goal of the game to make an immediate mark at the Greek side.
Sokratis was sent out on loan for the second half of the season at at Second Division side Niki Volou to get more first-team minutes under his belt.
Papastathopoulos started his first Champions League fixture in a 2-1 loss to French side Lille in the group stage in 2006.
He was widely praised for his man marking job on Italian legend Filippe Inzaghi in AEK’s 1-0 win over AC Milan in the Champions League in November 2006.
Sokratis became AEK’s youngest-ever captain at the age of 19 when he captained his team against their bitter local rivals Panathinaikos in 2008.
He scored two goals in 58 appearances for AEK.
Papastathopoulos completed a move to Serie A side Genoa for an undisclosed fee in 2008.
He made his debut in a 1-0 loss to Fiorentina in the Italian top flight in September 2008.
Sokratis netted his first goal for Genoa in his next appearances in a 3-2 win over Napoli.
24 days later, Papastathopoulos was on the score sheet again 2-1 victory over Cagliari.
He finished his first Serie A campaign with two goals and one assist in 21 league games.
Sokratis established himself as a regular in the 2009-10 season with 30 Serie A appearances.
AC Milan signed Sokratis in a €14m deal from Genoa in the 2010 summer transfer window.
However, the Greek defender made just six appearances in all competitions in a frustrating 2010-11 campaign. AC Milan won the Serie A title.
Sokratis was sent out on a season-long loan to Bundesliga side Werder Bremen on 21 July 2011.
He made his Bundesliga debut in a 2-0 win over Kaiserslautern on 6 August.
Papastathopoulos made 31 appearances in all competitions.
Werder Bremen made the deal permanent in a €5m in April 2012.
He remained a key player for Bremen but the German club spent the Bundesliga campaign battling relegation.
Sokratis made 30 appearances in all competitions.
Borussia Dortmund announced the signing of Sokratis on a five-year contract on the eve of their Champions League final in May 2013.
Jurgen Klopp spent €9.5m on the Greek defender to bolster his defensive options before Dortmund lost 2-1 to Bayern Munich in the European showpiece.
He made his debut for Dortmund in the Bundesliga in Borussia’s 2-1 win over TSV Eintracht Braunschweig on 18 August 2013.
Sokratis scored his only goal for the Bundesliga season in a 6-1 victory over Stuttgart on 1 November 2013.
He made one goal and two assists in 42 games in all competitions in the 2013-14 season. Papastathopoulos was named in the 2013-14 Bundesliga team of the year.
The Greek defender scored his first Bundesliga goal of the season in a 3-2 away win at Augsburg in August 2014.
Sokratis was on the score sheet against in a 1-0 win against Turkish side Galatasaray in the Champions League group stage in November.
His start to his second season at Dortmund was halted when Sokratis suffered a broken fibula in a 1-0 win over Borussia Monchengladbach on 9 November 2014.
Sokratis didn’t return until a goalless draw with Bayer Leverkusen on 31 January in 2015.
He still featured in 32 games throughout Klopp’s final season in charge at Dortmund.
Papastathopoulos signed a contract extension to ensure his stay at the Bundesliga club until 2019 on 26 October 2015 following interest from the Premier League.
Almost two months later, he scored in a 2-1 loss to Cologne in the Bundesliga.
He started Dortmund’s 4-3 loss to Liverpool FC in the second leg of their Europa League quarter-final in March 2016. Sokratis and his BVB team-mates came up against Klopp for the first time since the German head coach left the Westfalenstadion outfit.
Sokratis continued to establish himself as one of Dortmund’s key players in the 2016-17 campaign.
The Greece international got on the score sheet in a 6–0 win against Legia Warsaw in the Champions League group stage on 14 September 2014.
His second goal of the season came in a 3-0 win against Freiburg on 25 February 2017 before Sokratis scored for the third time in the season in a 3-1 victory over Frankfurt.
The powerful centre-half made 41 appearances in all competitions in his penultimate season at Dortmund.
He matched his tally in his final campaign at Dortmund.
Sokratis scored in a 3-0 away win at Cologne in September. The Dortmund defender scored his team’s only goal in a 1-1 draw with Apoel Nicosia in the Champions League group stage in October 2017.
His final goal for Dortmund came in a 2-0 win at Mainz 05.
Sokratis completed a £17.7m move to Premier League side Arsenal from Dortmund on 2 July 2018. He signed a five-year deal with the north London side.
Papastathopoulos made his Greece debut in a 1-0 win against Czech Republic on 1 February 2008.
He missed out on a spot in Greece’s Euro 2008 squad as his country looked to defend their European championship title.
Sokratis was sent off in Greece’s opening game against Poland at Euro 2012.
Papastathopoulos started all five of Greece’s games at the World Cup before they lost to Costa Rica on penalties in the round of 16.
He married his wife Xanthippi Stamoulaki in 2014.
Sokratis has two children.
• Born in Kalamata, Greece, the 26-year-old has the name ‘Sokratis’ on the back of his shirt because ‘Papastathopoulos’ is too long to fit.
• Sokratis was quick to win over Dortmund supporters after signing for the Bundesliga club when he arrived for pre-season in a modest Fiat 500.
• The new Arsenal signing scored at least one goal in every season he’s played in Germany, but never more than two.
• Sokratis is the first Greek player to represent Dortmund and Arsenal.
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