 In his first game in charge, they lost 1–2 to Germany in a friendly at Stadion Lohmühle in Lübeck, Schleswig-Holstein.Under Frederiksen, Denmark qualified for the UEFA European Under-21 Championship in 2017 and 2019, where they were knocked out in the group stages, finishing third and second, respectively.Frederiksen returned to club management at the beginning of the 2019–20 season with Brøndby IF, when the club announced him as their new head coach on 1 June.