|Full name||Mathias Aaris Kragh Nielsen|
|Date of birth||2 March 1991|
|Playing position||Centre back|
|2012||→ Viborg FF (loan)||9||(0)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 8 November 2015.
Mathias Aaris Kragh Nielsen (born 2 March 1991) is a Danish footballer. He plays at centre back for AC Horsens in the Danish First Division. Nielsen has 1 youth cap for Denmark, playing for the Danish under-20s.
Mathias Nielsen spent his entire youth career with Herfølge Boldklub, joining the club at 4 years of age, he went on to sign a contract with this childhood club in the summer of 2007. During the winter he would play indoor football with the team's indoor division, playing as goalkeeper. When Herfølge BK merged with Køge BK, Nielsen was carried over in to the newly formed club HB Køge.
1 July 2010 Nielsen moved to Superliga team F.C. Nordsjælland on a free transfer, signing a 1 year contract. He made his debut the following month as a substitute during the second leg of FCN's third qualifying round of the Europa League, against Portuguese side Sporting Lisbon. Amid interest from Italian clubs Parma and Napoli in March 2011, the young defender extended his contract with FCN for another two years.
17 July 2012, Nielsen left FCN for Næstved BK, having made a single appearance for the Farum club.
- As of July 1, 2012
- "INTERVIEW MED MATHIAS NIELSEN" (in Danish). Dansk Eliteungdomsfodbold. Retrieved 6 October 2011.
- Nielsen, Kasper (27 August 2007). "Herfølge skriver med syv ungdomsspillere" (in Danish). Bold.dk. Retrieved 13 August 2011.
- Houlind, Søren (10 April 2010). "FC Nordsjælland henter forsvarstalent" (in Danish). Bold.dk. Retrieved 13 August 2011.
- Helmin, Jesper (4 March 2011). "Italiensk interesse for FCN-spiller" (in Danish). Bold.dk. Retrieved 13 August 2011.
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