His last international match was a qualifier for the 2010 FIFA World Cup at home against Austria on 11 August 2008.
The club won the Faroese championship in 2011 managed by Mikkjal Thomassen and John Petersen.
[1] On 24 September 2020 under the management of Mikkjal Thomassen, KÍ became the first Faroese club to reach the play-offs in Europa League, when they won 6-1 in Tórshavn against the Georgian champions FC Dinamo Tbilisi.
[3] His first season in charge of FFK proved very successful, as he led the club to promotion to Eliteserien.
[6] Taking over with the club placed 8th in the Allsvenskan, Thomassen led AIK to 3rd by the end of the season, ensuring qualification for the UEFA Conference League in 2025.