 Born in Virum, he started playing football at nearby club Lyngby Boldklub at the age of six.He made his senior debut in 1975, in a Lyngby team which struggled to establish itself in the secondary Danish 2nd Division league.Berggreen was Lyngby's top goalscorer in several seasons, and scored 15 goals when the club won promotion for the top-flight Danish 1st Division in 1979.