VAL DI FIEMME, Italy – If an instant can last a lifetime, Marit Bjørgen (NOR) had more than enough time to watch the 2012 Tour de Ski slip away. Locked in a battle with rival Justyna Kowalczyk (POL) for eight races, Bjørgen matched the Pole stride for stride on the lower part of the final climb up the Alpe Cermis. An then, in that interminable moment, Kowalczyk was gone. The two-time defending Tour champion accelerated,...