Former Germany defender Arne Friedrich announced his retirement from football after suffering a long-standing back injury.
"After much consideration, lots of time in rehabilitation clinics and after a conversation with both my doctor and physiotherapist, I have decided to end my career," the 34-year-old said in a statement.
"In the last few weeks and months, I have had back problems. After two slipped discs, my body is no longer in the position to cope with the demands of being a professional sportsman."
Having made 82 appearances for Germany, the centre-back's single international goal came in the 4-0 rout of Argentina in the 2010 FIFA World Cup South Africa™ quarter-finals.
He was part of the Germany squad at the 2004 UEFA European Championships in Portugal, the 2006 FIFA World Cup in Germany, Euro 2008 in Austria and Switzerland, and the 2010 FIFA World Cup in South Africa.
He played for Hertha Berlin and Wolfsburg, making more than 200 Bundesliga appearances before joining North America's Major League Soccer (MLS) to play for the Chicago Fire last year.
"After my own wish, I have cancelled my contract with Chicago Fire and ended my dream career," Friedrich tweeted on Sunday having retired from international football in 2011.
"I wish the club and their great fans all the best. It has been a fantastic time with unbelievable experiences. I have won many friends in America and in Chico I have found a second home."