Career
At 206 cm (6"9"), he is one of the tallest playing football players. Playing as a reserve goalkeeper for Danish amateur club Fremad Amager, he was brought to English club Doncaster Rovers in May 2005. He signed a two-year contract and looked to compete for the starting goalkeeper spot with fellow Dane January Budtz.
One of the tallest players in the league, Nielsen was known as "The Gentle Giant" of football.
He did not find much playing time at Doncaster, and only played one game in the pre-season. He suffered injuries and was soon third goalkeeper choice at the club
He did appear on the pitch after a match against Manchester City, talking to January Budtz after the horrible scenes when Doncaster"s first choice keeper Andy Warrington broke his right legal Nielsen was eventually released from his contract in October 2006, and moved back to Denmark to play part-time football with Greve IF in the Danish 2nd Division.