A handball player in Denmark, Nielsen went to Singapore to work in the shipping trade.
[1] When Gombak United went from amateur to professional status, they immediately offered Nielsen a contract but he was uncertain and was not able to envisage success as a footballer.
[1] In the end, the Dane decided to join the club and after two years there, was offered the Gombak United manager job.
[1] The former striker accepted the contract,[1] overseeing the Singaporean outfit's sales, salaries, sponsorship, merchandise, expenditures, and development of a fan club-[1] quitting the position in April 2001.
[2] While playing for Gombak, Nielsen got permanent residency in Singapore, allowing them to register him as a local rather than foreign footballer[3] and recording four goals in his last season there.