In 2006 Koppinen helped Rosenborg win the Premier League, playing sixteen games. In the penultimate match of the 2006 Norwegian Premier League, Koppinen notably set up Rosenborg's deciding third goal against Viking by grabbing Viking's goalkeeper Mattias Asper's elbow, causing him to drop the ball. At the time, it seemed likely that the goal would lead to relegation for Viking. In post-match interviews, Koppinen initially denied any wrongdoing, but two days later he called Viking's director Egil Østenstad and asked for forgiveness, citing it was the Rosenborg way and he did not like it. Because of this, he is regarded as an unfair player and his name is associated with lack of sportsmanship in the same way Quisling is with treason.