This story has been updated. For the latest updates, click here.
12:40 A.M. UPDATE:
From Kyle Hopkins in Anchorage --
Four-time Iditarod Jeff King has scratched from the race at the Safety checkpoint, according to race officials.
Here is the full statement. Check back soon for updates.
"King indicated to Race Officials that the wind is severe in the area and he was having difficulty navigating the trail. He stayed with his team for approximately two and one half hours before asking a snowmachiner to help him by taking him to the Safety checkpoint to contact race officials. Jeff and others are moving the team to the Safety checkpoint for the night."
The National Weather Service has issued a brisk wind advisory for the Norton Sound, through Tuesday afternoon.
11:30 P.M. UPDATE: In a shocking reversal, Two Rivers musher Aliy Zirkle passed four-time Iditarod champion Jeff King to arrive first at the Safety checkpoint, just 22 miles from the finish line in Nome.
It was not immediately clear why King's team, which just hours before appeared out of reach for the surging Zirkle, stalled so late in the race. Zirkle averaged nearly 8 mph in the gusting coastal winds en route to Safety.
Check back soon for updates to this breaking story.
NOME -- During his eight-hour break Monday in White Mountain, Iditarod leader Jeff King said he wasn't celebrating a fifth victory quite yet.
"I'm not going to figure out what color truck I want till I get to Nome," he said, referring to the new truck awarded to the Iditarod champion, along with $50,000.
Too many unpredictable things can happen in the 77 miles between White Mountain and Nome, he said -- and he was right.
King's 57-minute lead over Aliy Zirkle vanished in the 55-mile run to Safety.
Zirkle, the two-time runnerup from Two Rivers, made up the gap and then some, reaching Safety at 10:53 p.m. She was a mile or two ahead of King, whose team -- according to the race's GPS tracking system -- stopped for some time.
Strong winds and limited visibility were reported in the area. Race analyst Joe Runyan of iditarod.com said "really ferocious" winds up to 45 mph were in an area known as a blow hole.
"The wind just starts to whistle," he said, "and I could see how it could demoralized a dog team and they'd say, whoa, we're gonna stop right here and we're not gonna move till this wind quits."
All of that is speculation.
What is known that Zirkle pulled off the improbable simply by catching King, an idea she entertained at White Mountain.
"I'm going to try to catch him," she said at that checkpoint. "The team looks good."
Barring more unpredictable turns, the Iditarod record book will need a rewrite by Tuesday morning. Zirkle -- driving a team led by a single dog, Quito, a female who helped Zirkle's husband win the Yukon Quest last month -- was on record pace late Monday.
If Zirkle wins, she would be the third woman in race history to claim a championship and the first since Susan Butcher in 1990.
If King, a 58-year-old from Denali Park, is able to rally and reclaim the lead, he would be the oldest winner and would match Rick Swenson for the most victories in the 42-year history of the race.
The milestones are coming despite a trail that hardened veterans described as the most dangerous ever.
A veteran of 24 previous races, King wasn't taking anything for granted despite his comfortable lead in White Mountain. As his mandatory eight-hour layover expired, just before he set his team trotting up the Fish River kicking from his sled runner, a race fan offered him congratulations.
"Well, we'll have to get through this run and then we'll party," King said.
King caught Zirkle in Koyuk, 94 miles up the trail, pulling into that checkpoint one minute behind her and leaving it one minute ahead of her. It was the first time he'd seen her for the entire race, he said.
Out of Koyuk the trail had started rough -- "logs and ice and turns and rocks," King said -- but the team eventually picked up speed.
King said he thought he had pulled away from Zirkle on the run to Elim, but Zirkle was only a few minutes behind.
"As I have done many times, I underestimated the speed of her team, or what she'd get out of it," King said. "She must've had a great run, too, because mine was really, really great.
King opened the gap he was hoping for on the run from Elim to White Mountain.
He reached White Mountain in the pre-dawn darkness where, instead of the usual church bells, subzero temperatures and wind greeted him.
King praised his lead dogs: mother-and-daughter team Skeeter and Zig. They had gotten him across windy and frozen Golovin Bay by bee-lining from trail marker to trail marker while the gusts sent his team skittering across the glare ice.
A faint morning light shone on the horizon as Zirkle's headlamp came into view downriver. Asked how he felt about his lead, King said, "Better every minute."
As Zirkle parked, she said she had trouble leaving Elim. Her prized lead dog, Quito, chewed through the line connecting her to the rest of the team there. When King left, so did Quito. It took some time to wrangle the leader, Zirkle said.
"I knew there were dog eyes, I just didn't know which ones were hers," Zirkle said. "I feel like I got a little far behind."
"I'm happy to be here," she said. "It's so funny, this part of the race. You look forward to the race all year, and you enjoy the race, and then you get here, and you're like, 'Oh my god, I want it to end!' ''
In White Mountain in third and fourth place were 2012 champion Dallas Seavey and his dad, defending champion Mitch Seavey. Both had run similar races, building up their teams in the early days of the race rather than building big leads, and then marching past many others whose dogs were tiring.
For both Seaveys, the competition was so far ahead or so far behind them that they only had to focus on finishing.
"I'm just enjoying the moment," Mitch said while pouring hot water on a mixture of frozen meat and dry dog food. "It's very enjoyable for me, because I have no pressure."
Along with King and Zirkle, the Seaveys were set to break Kotzebue musher John Baker's 2011 speed record of 8 days, 18 hours, 46 minutes, 39 seconds.
A trail notable for lots of ice, lots of dirt and not much snow, helped make that possible, Dallas said.
"It's brown alright, but there're little pockets of (frozen) water, and between these little frozen puddles, it makes a rather slick surface, and the dogs have no resistance on their legs (like) going through snow," he said. "Every time they plant their foot, it's like a runner running on a nice sticky track, rather than dirt track or a grass field, where there's some slippage.
"So the dogs have good traction, the sleds slide well, and, man, these guys have been ripping down the trail. And our brakes don't work, so it speeds us up a little bit."
Complete Iditarod coverage
By CASEY GROVE