As one of the U-21 profiles, Christjansen trained with the first team on occasion and appeared on the first-team bench several times under coach Tom Køhlert in 2007.

[2] On 24 January 2009, in search of more playing time, Christjansen signed with Lolland Falster Alliancen in the bottom of the Danish second tier.

Frem went bankrupt at the end of the season and were demoted to the Copenhagen Series, the Danish fifth division, effectively making Christjansen a free agent.

[4] Following Frem's bankruptcy, Christjansen signed with Hvidovre IF, which allowed him to continue playing in the second tier on an amateur contract.

[10] The season became an overwhelming success for Christjansen and Lyngby, as the club reached Europa League play-offs after securing a third place in the Superliga.