After leaving school in 1985 Nielsen trained as a police officer but resigned after 11 months. He then worked as a truck driver for a Formula One catering company. In 1986, he joined
Team Lotus' test team, He joined
Williams as Sporting Manager in December 2014 and worked in that role until leaving in July 2017, being replaced by
Dave Redding. On 1 August 2017 he started in a new position as the Sporting Director of Formula One. He left this role and became the
FIA Sporting Director on 18 January 2023. In December 2023, Nielsen left the FIA after 11 months in the position. On 4 July 2025, Nielsen was announced as the successor to former Team Principal
Oliver Oakes and will be taking on the new position of "Managing Director" of the
Alpine F1 Team, running the day-to-day operations of the team from 1 September onwards, ahead of the Italian Grand Prix at Monza due to his expected gardening leave following his departure as Chief Motorsports Operations Officer, Sporting from commercial rights holder F1 and will report to
Flavio Briatore who will continue to have overall responsibility of the project. ==References==