Hermann Gerland, head coach of Arminia Bielefeld at the time, scouted Friedrich while playing for Regionalliga club SC Verl.

Because of his convincing performance, Gerland decided to bring Friedrich to Bielefeld, where he immediately became a regular starter.

With the Berlin club, he won the DFB-Ligapokal that year, defeating Bayern Munich, Borussia Dortmund and Schalke 04.

[3] However, after Hertha's relegation in 2010, Friedrich left the club in a €2 million transfer[4] to VfL Wolfsburg, signing a three-year contract.

[10] As announced on 21 January 2013, Friedrich became a US permanent resident which allowed him to no longer occupy an international slot while playing for Major League Soccer clubs.

Following an injury to Marcell Jansen, he started the final group game and all three knock-out stage matches.

The quarter-final was one of Friedrich's best international matches where he successfully shut down Portugal national team star Cristiano Ronaldo.

In March 2009, German coach Joachim Löw explained that he now planned Friedrich as a centre-back instead of the right wing-back position.

After a Bastian Schweinsteiger solo run, he scored his very first international goal on his 77th appearance[4] for Germany on 3 July 2010 in the 2010 World Cup 4–0 quarter-final win over Argentina.