In October 2013, it was announced that Guðmundur would take over as the head coach the Danish men's national handball team on 1 July 2014, replacing Ulrik Wilbek . On 21 August 2016 Guðmundur led his team to the gold medal at the 2016 Summer Olympics in Rio de Janeiro, Brazil. During the Olympics, Wilbek made two attempts to gain the consent of the Danish players to fire Guðmundur, once during the tournament and then the day after Denmark won the gold. He announced in November 2016 that he would not renew his contract, which was set to expire on 1 July 2017. After his departure from the Denmark team, Guðmundur criticized his predecessor Wilbek's, who was then the head of the Danish Handball Federation, repeated attempts to undercut his management of the team during the Olympics.