Mertesacker is an exceptional defender for Arsenal and for the German national side - having been capped 79 times for his country. He began his professional career in the youth system of home-town club Hannover 96.
The tall and lanky defender made his debut for the team in the Bundesliga in 2003, aged 19, and he impressed over three seasons with the Reds for his disciplinary record - once going 31 games without a booking - and his solid defensive play - earning the nickname The Defence Pole.
During this time Mertesacker also made his debut for the German national side, debuting against Iran in 2004. By the time the 2006 World Cup came around, Mertesacker was the first choice centre-half for Germany as they hosted the tournament, and came third. His showings convinced Bundesliga heavyweights Werder Bremen to move for him, securing Per in a €5 million deal in 2006. Mertesacker would go on to play more than five seasons for the Green and Whites, wearing the number 29. He got exposure to European continental competition during this time, and was important in helping the club to the Bundesliga crown in 2008-2009. This was his greatest achievement at Bremen.
Following a less than impressive start to the season, Arsenal manager Arsene Wenger signed Mertesacker in August 2011, bringing the defender to England. Given the number 4 shirt, Per has begun to adapt to the speed of the English Premier League. On the international stage, Mertesacker has remained Germany's best centre-half since his debut. He played in the final loss at Euro 2008 to Spain, and in the third place finish at the 2010 World Cup. His record for Germany at still such a young age is impressive.