Collberg grew up on the island of Frösön with long alpine skiing boards, when he was ten years old he started telemarking. In 2005 he took part in the championships in Åre . On January 30, 2010 he made his debut in the Telemark World Cup , only competed in two World Cups during the season, which he finished with midfield results. In the overall World Cup ranking, he took 45th place, 43rd place in Classic, 55th in Classic Sprint and 38th in giant slalom. In the 2011 season , he started in the middle of the season and took part in four World Cups. His best result was an 11th place in Classic Sprint races at Thyon . Otherwise he achieved results around places 20 to 17 except at the World Cup in Hafjell , where he achieved his poor World Cup result with 34th place in the Classic Sprint race. In the overall World Cup ranking he came in 28th place, in the Classic on 18th place, Classic Sprint and in the giant slalom on 34th place. For the very first time he took part in the 2011 Junior World Championships in Hafjell. With fifth and sixth place he achieved good results in the classic races and in the giant slalom. In the Classic Sprint he was 15. A week later he took part in the 2011 World Championships in Rjukan . The world championships are not going so well with one exception with 14th place in the giant slalom. He was 27th in the Classic and 20th in the Classic Sprint. By the middle of the 2012 season he achieved results in the top ten, finishing 10th twice, eighth and sixth twice. He was able to maintain his good performance, which he had until the middle of the season, until the end of the season. At the finale in Espot , he achieved his best result of the season in fourth place in the Classic Sprint race. In the overall standings and in the Classic Sprint, he took 11th place, in the Classic 16th place and in the Parallel Sprint eighth place. At his second Junior World Championships in 2012 in Espot, he won the silver medal in the Classic Sprint, fourth place in the Parallel Sprint and Collberg did not finish in the Classic. On January 6, 2013 he was fourth in the FIS race in Aandalsnes .
In the 2013 season he finished in the top ten in several races. At the first World Cup station in Bohinj , he finished fourth. In the overall World Cup and parallel sprint he finished ninth, Classic on 14th place, Classic on sixth place. In his third participation in the Junior World Championships in 2013 in Vallée de Chamonix , he won the silver medal in the Classic Sprint and fifth place in the Classic. The 2013 World Championships were mediocre. In the Classic, Collberg was not at the start, in the parallel sprint he came in fifth place and in the Classic Sprint he missed the top 15 places with 16th place. In the 2013/14 season he clinched his first podium with second place in Geilo , the other races are mediocre and he did not finish in three races. At the end of the season he finished ninth in the overall World Cup standings, ninth in the Classic, 11th in the Classic Sprint and sixth in the parallel sprint. The last Telemark Junior World Championship in 2014 went off quite well, he won the bronze medal in the Classic Sprint race and fifth in the Classic and Parallel Sprint. At the beginning of the 2014/15 season , Collberg achieved his best result of the season with fourth place in Hintertux . In the rest of the season he drove in midfield results. In the overall World Cup ranking he finished 11th, 12th in Classic, tenth in Classic and sixth in parallel sprint. At his third Telemark World Championship in 2015 , he also finished the races in midfield.
Sweden
