Norway's Petter Northug crosses the finish line to win the men's cross country 50 km mass start classic race at the Nordic World Ski Championships in Falun March 1, 2015. Norway's Petter Northug won the race ahead of Lukas Bauer of the Czech Republic on second place and Sweden's Johan Olsson on third place. REUTERS/Kai Pfaffenbach (SWEDEN - Tags: SPORT SKIING TPX IMAGES OF THE DAY)