 The departure of first-team profiles such as Mikkel Rygaard and talents such as Bror Blume, due to relegation and Lyngby's poor financial situation, meant that Marcussen saw more playing time during the 2018–19 season.He had an eventful season, making 28 total appearances in which he scored two goals.The campaign culminated with a third place in the league table and promotion play-offs, which Lyngby won 4–3 over two legs against Vendsyssel FF and thereby secured promotion back to the Superliga after one year.