Nielsen has become a solid NHL'er. Nielsen is a very smart player and a skilled playmaker, with great hockey sense, he reads the game well and he is a good skater. Which allows him to fill a role on both the power play and penalty kill on the New York Islanders team. Has in recent years been considered an outsider for the Selke Trophy. And is among the most underrated players in the NHL according to Sports Illustrated and the NHLPA player poll.
- 2007-01-06 • Debuted in the NHL against the Carolina Hurricanes.
- 2007-01-06 • First Danish player in the NHL.
- 2010-02-10 • Reached his 100th NHL point against the Montreal Canadiens