Fetterlein won his first tournament on the ATP Challenger Tour in 1988 together with Nicklas Kulti . In the following years he played successfully on the Challenger and Satellite Tour, where he was able to win several tournaments. In 1991 he won his first game on the ATP Tour , but there he was never able to prevail. He celebrated his greatest success on the ATP Tour in 1997 at the side of Kenneth Carlsen when he reached the double finals of the Copenhagen indoor tournament . He reached his highest ranking in the tennis world rankings in 1995 with position 75 in the individual. In Grand Slam tournaments, he never got past the second round.
Between 1989 and 2003 Fetterlein played 35 singles and 13 doubles for the Danish Davis Cup team . He achieved individual victories against Goran Ivanišević and Stefan Edberg . He played his last professional match as part of the Davis Cup 2003 in September when Denmark played South Africa in Bronby .
He joined the 1992 Summer Olympics and in the 1996 Summer Olympics to Denmark. At the side of Kenneth Carlsen, he was eliminated in the first round of the doubles competition. In 1996 he reached the second round after defeating Jacco Eltingh , but lost there to Marc Rosset .
Denmark