In November 2001, he signed a three-and-a-half-year contract with Aalborg Boldspilklub (AaB) in the top-flight Danish Superliga championship.

On 6 July 2007, Würtz moved to league rivals Copenhagen, signing a five-year-long contract with the defending Danish champions.

In July 2009, Würtz was transferred back to AaB, signing a four-year-long contract with his old club, as his Copenhagen career did not seem to improve.

While playing for Skive, Würtz represented Denmark in various youth national teams, and competed at the 2000 Under-17 European Championship.

When he approached Gravesen, he was told to take the armband himself and thus he captained the Danish national team for the final nine minutes of his debut game.

Having received his senior debut for Denmark, Würtz captained the Danish under-21 national team, as it qualified for the 2006 European Under-21 Championship in May 2006.

[10] He was the Danish under-21 team captain at the tournament, playing full-time in Denmark's three matches, and scored a goal against the Italian u-21s.