his first goal for Schalke in a 6–1 win over HJK Helsinki. On 1 December, in a group stage game in the Europa League, Papadopoulos scored the opening goal in a 2–1 win over Steaua București. On 17 December, Papadopoulos scored his first goal in the Bundesliga in a 5–0 win over Werder Bremen and scored the next game on 21 January 2012 in a 3–1 win over VfB Stuttgart. Since joining Schalke from Olympiacos, Papadopoulos has played in over 70 matches in all competitions, scoring five goals and has ultimately gathered respect and praise from all over Europe due to his tenacious and skillful defending considering his young age. Ahead of the 2012–13 season, Italian club Milan were interested in signing Papadopoulos. After showing interest, Schalke accused Milan of making an illegal approach for Papadopoulos without the club knowing. Also interested were Russian giants Zenit Saint Petersburg, but when their £16 million bid for Papadopoulos was accepted by Schalke, Papadopoulos rejected the move, opting to stay in Germany. In September 2012, Papadopoulos signed a new contract with Schalke that will keep him at the club until 2016. On matchday two of the 2012–13 season, Papadopoulos scored his first goal of the season, and third in the Bundesliga, in a 3–1 win over FC Augsburg. A virus, however, would later kept him out of play for a number of games, and he would later undergo surgery in an attempt to correct a knee injury he suffered in a 3–1 loss away at Hamburger SV in November 2012. After a very difficult year for the defender marred by injury (383 days to be exact), Papadopoulos returned to action in a home game against SC Freiburg in December 2013. Just a few weeks after his return to action, however, Papadopoulos suffered a new shoulder injury and could have been forced to undergo surgery. The news came as another blow, as his recurring knee problems restricted him to just four appearances in the 2013–14 season. The injury also forced him to miss the 2014 World Cup with Greece. Loan to Bayer Leverkusen On 3 August 2014, Bayer Leverkusen signed Papadopoulos on a season-long loan deal. He told Leverkusen's official website, "I am very happy that it worked out with the change. Bayer 04 is a club just like Schalke with major international ambitions. Unfortunately I was injured more often in the past season.