Career
He played 362 matches and scored 42 goals for Danish club Esbjerg fB, and played for a number of European clubs. Born in the Esbjerg suburb of Guldager, Bertelsen started playing football with small-time club Sædding-Guldager. When Sædding-Guldager coach and former Danish international Egon Jensen was hired by 3rd Division team Esbjerg fB, Bertelsen followed him to the club, where he played alongside later Danish internationals Ole Kjær, Ole Madsen, and John Lauridsen.
He made his Esbjerg debut at the age of 21, on 1 April 1973.
He received a number of offers from European clubs, and decided to move abroad in May 1982. He signed a professional contract with Belgian club R.F.C. Seraing, and quickly settled into the team
He stayed two years in Belgium, before moving on to French outfit Rouen Football Club when Seraing went bankrupt in 1984. After one season with relegation battlers Rouen, he moved to Swiss team Football Club Aarau in the summer of 1985.
Bertelsen returned to Esbjerg fB in 1987, where he ended his career at the end of the 1988 season.
Bertelsen made his international debut with the Denmark national under-21 football team in May 1975, and played five under-21 games until October 1975. He was called up for the senior Danish national team by national manager Kurt "Nikkelaj" Nielsen, and made his national team debut in a 0–0 draw with Norway on 24 June 1976. He played his second game in February 1978, and went on to become a mainstay in the team under new national manager Sepp Piontek.
Bertelsen had a somewhat anonymous role in the defensive midfield, though his work rate made him an integral part of the team
While playing abroad, Bertelsen was called up by Piontek to represent Denmark at the Union of European Football Associations Euro 1984. He played full time in all Denmark"s four games before elimination in the semi-finals.
He played three of Denmark"s four games at the tournament. He played his last national team game in September 1987, at the age of 35.
1976 Danish Cup.