 Gjertsen was traded to Montreal Impact on July 26, 2007 along with midfielder David Testo for midfielder Zé Roberto and forward Alen Marcina.On October 24, 2007 he signed a two-year deal with the club.He played an important role by starting all 10 games in Montreal's 2008-09 CONCACAF Champions League run, scoring in the first leg of Montreal's preliminary round tie against Real Estelí of Nicaragua, which saw Montreal through to the Group Stage.