2008-09: Spent most of the season with Skelleftea’s J20 team at the junior level. In 28 games, Pettersson scored 5 goals and added 9 assists for 14 points. He added 24 penalty minutes to those offensive totals. He picked up no points in 5 playoff games.
2009-10: Once again playing for Skelleftea in the J20 Superelit, Pettersson scored 11 goals and added 20 assists for 31 points in 37 games. At the U-18 World Junior Championships, Pettersson had 1 assist in 6 games for Sweden.