Sundby's strongest competition during that season's Tour de Ski. Despite leading before the final climb up the Alpe Cermis, he lost to Sundby, who won his second TdS title in a row. In July 2016, Sundby lost that title to Northug after Sundby's anti-doping rule violation, thereby giving Northug his first Tour de Ski win. At the 2015 World Championships in Falun, Northug secured his 10th WC gold medal by narrowly beating Canada's Alex Harvey in a bunch sprint to the finish line in the men's classic sprint event. He then proceeded to contribute to Norway's victory in both the team sprint and 4x10km relay. The final race of these World Championships, i.e. the 50 km classic, saw Northug notch a notable victory. The race was held in difficult conditions due to heavy snowfall; sitting at third in the last climb before the finish, Northug, in a remarkable display of double poling, managed to overtake his remaining two opponents to win the race. As of 2015, Northug had won 20 Olympic and World Championship medals (15 gold, 4 silver, 1 bronze). He announced his retirement from cross-country skiing on 12 December 2018. Career after competitive skiing As late as 13 August 2020 he was doing occasional work as a celebrity at summer camp for teenage skiers. In August 2020 Uno-X said that their sponsorship deal with Northug would be canceled in the near future, due to [the company's view that] Northug "must concentrate about other things". In November 2020 he released a Christmas song, "Petters Jul". Personal life He has two brothers, Even and Tomas. Tomas Northug also skis professionally and won the Junior World Championships in sprint in 2010. Northug finished school in 2006, but during the summer of 2005 he changed schools from Steinkjer to Meråker and moved into a cabin next to the ski trails to optimize his training conditions. Northug is an active poker player, and has openly supported the legalization of poker in Norway, which is currently illegal when prizes are involved under Norwegian gambling laws. He participated and cashed (on 653rd place) in the 2010 World Series of Poker main event which he played with skiing rival Marcus Hellner. Northug is featured in the music video "Rise Again" by Jack Taylor, featuring Mo of Norway. Substance abuse and traffic violations In the early hours of 4 May 2014, Northug crashed his car, an Audi