He was soon dubbed "the Defence Pole" ("die Abwehrlatte") by German tabloids, and gained a reputation for his exceptional disciplinary record, going 31 league games without being booked.

After being singled out for praise for his performances at the 2010 FIFA World Cup, and with his contract at Bremen dwindling, he transferred to Premier League club Arsenal a year later, for a fee of £8 million.

[10] He eventually built up a solid relationship with fellow defender Laurent Koscielny, and the duo would star as Arsenal ended their nine-year trophy drought by winning the 2014 FA Cup.

Upon his debut, Mertesacker established himself as Germany's first-choice centre back for ten years, participating in UEFA European Championship in 2008 and 2012, as well as the 2006, 2010 and 2014 FIFA World Cups, winning the latter.

[16][17][18] He began playing football alongside his brothers at the local amateur club TSV Pattensen before joining Hannover 96, where their father was a part-time coach.

[19][20][21][22] As a youth player Mertesacker was neither a highly regarded prospect or had any ambitions of being a professional footballer and chose to study for his abitur with the goal of entering tertiary education.

[24] While juggling his football commitments and training, he completed his 'Abitur' at Carl-Friedrich-Gauß-Schule, a comprehensive school located in nearby Hemmingen noted for its sports program,[25][26] and subsequently carried out his 'Zivildienst'[27] at a centre for handicapped people in Hanover.

[32] Having established himself as first-choice centre back, his strong performances and clean disciplinary record did not go unnoticed by new national team coach Jürgen Klinsmann, who called him up and eventually handed him his senior international debut in October 2004.

[35][36] In August 2006, Mertesacker moved to Werder Bremen in a €5 million transfer deal after a highly impressive performance in the 2006 World Cup, in which Germany finished third.

He scored the opening goal in the DFB-Pokal semi-final away at northern rivals Hamburger SV to break the deadlock after a goalless first half, but the home side equalised, forcing the match into extra time and Bremen eventually triumphed 4–2 on penalties.

"[50] Mertesacker captained Arsenal for the first time in the FA Cup win over Brighton & Hove Albion in January, and appeared in every game save for the draw at Southampton on New Year's Day.

[62] After initially featuring sparingly due to injuries in the 2014–15, he returned to captain Arsenal in the 2015 FA Cup Final at Wembley in a 4–0 victory over Aston Villa.

With Arsenal making a charge towards the title, Arsène Wenger singled out Mertesacker for praise, calling him an "important leader in the dressing room and a respected one".

[64] On 24 January 2016, in a match against London rivals Chelsea, Mertesacker was sent off after 18 minutes for a late tackle on Diego Costa, who later scored the only goal of the game at Emirates.

He made a number of important tackles during the match and his performance was praised by opposition manager Antonio Conte, who stated that Mertesacker was a "perfect example for any young professional football player," adding that "what he did today was just a consequence of an unbelievable attitude every day.

With his quiet but effective game, he established himself as Germany's first-choice centre back,[71] pairing up with Robert Huth, Christoph Metzelder, Heiko Westermann and later Arne Friedrich.

At the 2005 FIFA Confederations Cup hosted on home soil, he played the full 90 minutes in all five games and scored his first international goal in a group stage match against Australia as Germany finished in third place.

After Germany's loss to Italy in the semi-finals, Mertesacker had surgery on one of his legs and left testicle (not related to the attack above, but an injury he had been dealing with during previous matches) and missed the third place play-off.

Mertesacker was called up for the 2012 European Championship but spent the whole tournament on the bench as an unused substitute due to the emergence of youngsters Mats Hummels and Holger Badstuber.

[74] On 19 November 2013, Mertesacker captained the side and also scored the winning goal as Germany beat England 1–0 at Wembley Stadium in a friendly match to mark the 150th anniversary of The Football Association.

[75] During the 2014 World Cup qualification campaign, Mertesacker contributed two goals and also re-established himself as first-choice centre back following a long-term injury to Badstuber in the middle of the 2011–12 season, often partnering either Hummels or Jérôme Boateng.

[80][81] During the 2014 World Cup Mertesacker became an internet sensation after a video of his live post-match interview was uploaded on YouTube and went viral, amassing over 28 million views as of June 2015.

[86][87] Journalist Raphael Honigstein and national team manager Oliver Bierhoff both retrospectively noted that the infamous interview was a turning point for the squad psychologically.

[101] Often, Mertesacker is paired with a more mobile and quicker defender who can track-back in a counterattack situation, such as Mats Hummels and Arne Friedrich for Germany, Naldo at Bremen, or Laurent Koscielny at Arsenal.

Mertesacker met his future wife German international handballer Ulrike Stange in 2008 while both were recovering from injury at a rehab clinic in Donaustauf and began a relationship not long after.

[29] The well-publicised interview drew criticism from some current and former players but he was generally praised by many others, including professional sports psychologists and his former teammates,[104][105][106] for his candidness and courage in broaching a sensitive topic and addressing the perception that footballers were "perfect".

After Enke's suicide it began focusing on providing support for those suffering from depression and has since expanded to include disadvantaged and marginalized children, particularly those from immigrant backgrounds, in his native Hanover.

Since 2007, the foundation has organised yearly charity football matches which have featured Mertesacker's national and club teammates Philipp Lahm, Lukas Podolski and Tomáš Rosický, as well as comedian Oliver Pocher, Fury in the Slaughterhouse member Rainer Schumann and German ice hockey legend Uwe Krupp.

T-shirts and sweatshirts bearing the words "Big Fucking German" – the Arsenal fans' chant for him and a play on the Roald Dahl novel The BFG[111] – are among items sold to raise money for the foundation.

[112] Mertesacker co-owns the Hanover-based real estate agency CP Immobilien GmbH with his Werder Bremen and national teammate Clemens Fritz.