At dawn on March 11, former Iditarod champion Mitch Seavey arrived with 10 dogs in Koyuk, a village on the Seward Peninsula and the prospect of a second Iditarod title just 170 miles away. Seavey had covered 50 miles from Shaktoolik to Koyuk at an average speed of 7.75 mph.

But as he rested his team, four-time Iditarod champion Jeff King came through the checkpoint, grabbing the lead in the 1,000-mile race across Alaska for the first time. For veterans King, 57, and Seavey, 53, a head-to-head encounter is nothing new. They've been matching dog teams at Alaska's top sled-dog races for decades.

READ MORE: 2013 Iditarod Trail Sled Dog Race