KOYUK -- As four-time Iditarod champion Jeff King approached this village just 170 miles from the finish of the Iditarod Trail Sled Dog race, he glanced up and saw what he first thought was a mirage.

In the distance, a ghostly figure in white slowly moved toward the Seward Peninsula community. But it was no mirage. It was Aliy Zirkle of Two Rivers, the leader of the world's premier distance sled dog race, wearing a white wind suit. And Zirkle was a vision of hope that the 58-year-old King might finally be able to join Rick Swenson as the race's only five-time champions. Days ago, King was hours behind. Now, he was neck and neck -- pulling in just a minute behind Zirkle before grabbing the lead by leaving one minute ahead of her at 5:50 p.m. By Monday morning, he'd extended his advantage, leaving the Elim checkpoint eight minutes in front of Zirkle and pulling into White Mountain at 7:02 a.m. for a final eight-hour rest before the stretch run to the Nome finish line.

"I was thrilled," King said of seeing Zirkle as they approached the checkpoint. "I thought I was close, but maybe not that close."

And the thrill of a pitched battle energized his every move. King skidded into his parking spot here with a full cooler of dog food. After setting his hook, he grabbed the blue-and-white container and went to laying out food for his dogs rapidly -- spreading it on the snow for them to snack on -- only to come back a moment later with a full blue plastic bag of straw. He covered the dogs, building little nests for leaders like Barnum, a tall back dog who has led his most of the race, and his mother, Skeeter, who took over on the treacherous trip from Shaktoolik, the previous checkpoint some 50 miles back down the trail.

Bitter cold temperatures

Despite sunshine and a temperature of about zero degrees, a harsh wind blew, making everything even more difficult to handle. King called it some of the coldest racing he's ever endured.

Zirkle felt the chill, too. She tried to stay warm by using ski poles or crouching down behind her sled, alternating between the techniques when she was too cold just standing on the runners. Frigid air wasn't the only problem for Zirkle, who has finished second to Mitch and Dallas Seavey in the last two Iditarods.

Zirkle tweaked her hamstring on the icy trail as she came into the Shaktoolik checkpoint early Sunday morning. She said she'd tried massaging it, which helped a little, but the muscle still ached Sunday afternoon.

She wasn't the only musher tending to an ache. Martin Buser of Big Lake, the third musher into Koyuk, more than two hours behind Zirkle, asked for help fixing a makeshift splint he put together with modified dog booty Velcro to help him deal with the sore and swollen pinky finger he's nursed for hundreds of miles. The finger kept popping out of place, and Buser was massaging it again as he went about his dog chores Sunday afternoon.

Also achy was Zirkle's lead dog, Quito. She said she'd massaged her trusted veteran leader, who's pulled Zirkle to her two Iditarod second-place finishes as well as victories in the Yukon Quest International Sled Dog Race in front of Zirkle's husband, Allen Moore. Zirkle said she could use other leaders in her team, but none were as speedy as little Coyote-like Quito.

Seavey looms not far behind

But early Sunday afternoon, after arriving here, Zirkle parked and set down her snow hook, moments after nearly losing her sled in a ditch coming into the checkpoint. She then walked up and down the line, feeding her 11 dogs, all of whom stood patiently awaiting snacks. Then she grabbed a large bale of straw, shaking out armfuls over the dogs, who quickly snuggled in. Off came their booties and more snacks were delivered before Zirkle fired up her cooker to finish preparing a stew of kibble, meat and fats for the animals.

King was the first musher out of Koyuk, back on the trail at 5:50 p.m., with Zirkle following a minute later. With some minor deviations, the trail will follow its traditional route for 48 miles to Elim, the next checkpoint just 125 miles from the finish line. But after Elim, things could get rough. A lack of sea ice has forced Iditarod organizers to reroute the trail. Instead of following the ice for eight miles along the coast before turning inland, the teams will follow the sea ice for a mile out of Elim and then head inland. It's hilly terrain with little snow and it includes 1,000-foot-high Little McKinley, the tallest peak on the Seward Peninsula, and Walla Walla, another big hill. After clearing them, mushers descend into White Mountain where they will take their final eight-hour mandatory break before racing the final 77 miles to Nome.

Zirkle and King have other challengers to fend off, including 2012 champion Dallas Seavey of Willow, who zoomed through his dog care here, rapidly pulling off booties, laying down straw and warming water for his animals. Seavey was more than two hours behind the leaders into Koyuk, but he was making a late-race charge.

Seavey looked alert and spry as he warmed his food in the community hall, staring at the latest stat sheet, trying to deduce where he fit against everyone's run times.

After a few minutes and a few calculations on his fingers, he mumbled "all right" and headed back to his food.

Just a half hour earlier he'd leaned into his wheel dog, Glitter, and muttered something else.

"I don't know if we can catch 'em, but we sure can scare 'em."