Career
Bak Nielsen usually plays central defender, but he has a past as a striker. He has played one game for the Danish under-21 national team Bak Nielsen started his senior career with (FCM) in 2000.
In his first years at FCM, he played as a striker, but eventually settled as a central defender.
He played all FCM"s matches during the 2003-2004 Superliga season, and was called up for the Danish under-21 national team in October 2003. He played a single under-21 national match, against the Bosnia & Herzegovina under-21s.
He prolonged his FCM contract in November 2004, and went on to become captain of FCM during 2005. On 20 November 2006, he was called up for the Danish league national team, playing unofficial games against the United States, El Salvador and Honduras in January 2007, by national team manager Morten Olsen.
He was called up for the Danish national team in March 2007.
On 19 June 2007, he signed a four-year contract with the Dutch team He was sidelined with an ankle injury from the end of the December 2007. He made his league return in October 2008, against Ajax.
In 2010 Bak Nielsen moved back to
