Emily Sweeney of the United States takes a luge training run at the 2018 Winter Olympics in Pyeongchang, South Korea, Saturday, Feb. 10, 2018. (AP Photo/Andy Wong)

PYEONGCHANG, South Korea (AP) — Tucker West was absolutely flying. He was leading the Olympics, at least through the midway point of the opening run. He set a start record. He looked very much like a medal contender.

And then came Curve 9.

In an instant, West’s medal hopes in the men’s luge competition were gone.

No matter the sport, no matter the nationality, there’s one thing the world’s best sliders can all agree on at the Pyeongchang Games. In bobsled, skeleton and luge, Curve 9 — a tricky little spot about halfway down the track at the Alpensia Sliding Center — will be the turn where Olympic medals might not be won, but definitely can be lost.

“I knew it was going to be a challenge coming in,” West said Saturday night, not long after the run that he’ll be replaying in his mind for at least the foreseeable future. “I was getting confident with it throughout the week. I nailed it six runs in a row. Just made an unfortunate mistake … and I paid for it.”

He was the first to get really bitten there. He won’t be the last.

Getting through that curve has been the talk of the sliding community for the last year, with everyone wondering the best way to navigate perhaps the most befuddling stretch of track in the world. Many struggled Saturday night, and many more have struggled with it during training in recent days.

“The one who wins,” German luge star Felix Loch said, “will be the one who has four clean runs.”

Notice that Loch didn’t say fast runs, or great runs. Just clean runs. That’s what he did on Saturday night when he grabbed the lead at the midpoint of the men’s luge competition, putting him in position for a record-tying third consecutive gold medal. Ordinarily, Loch would be a lock. Curve 9 will make these Olympics anything but ordinary.

“You’re going to see a lot of jostling throughout the standings,” U.S. men’s skeleton veteran Matt Antoine said, speaking primarily about his sport but offering perspective shared by both lugers and bobsledders as well. “It’s going to be tough for an athlete to have four really good, consistent runs. I think it’ll be a really good, competitive race.”

The sliders who can come out of Curve 9 – one of 16 curves on the track – cleanly may save themselves a half-second or more. And in sliding, a half-second is an eternity. In the luge race Saturday night, a half-second was basically the difference between first and ninth place.

So what’s the secret?

If anyone knows, it’s Aileen Frisch. She’s a German-born luger who obtained South Korean citizenship leading into these Olympics because she was no longer going to be part of her homeland’s national team, and the hosts in Pyeongchang needed to find depth in plenty of sports. Being part of the host nation’s team for these games means she’s had far more runs on the Alpensia track than any international slider, meaning she knows all the tricks.

Not surprisingly, she’s not saying.

“Sorry,” Frisch said, smiling while shrugging her shoulders.

Ask the U.S. women’s lugers about Curve 9, and they’ll all either groan or laugh. Emily Sweeney said it’s like driving on a slanted road, but having your car getting pulled in a direction away from the way you’re steering. Erin Hamlin said she’s sending the turn positive vibes, with hopes that the curve will return the favor. Summer Britcher said it’s tricky, but thinks the key is coming out of Curve 8 the right way to give oneself a fighting chance.

“Everything about this sport is hard to explain,” Britcher said. “And this is an exceptional, unique thing.”

Track workers have made some mild tweaks to Curve 9 over the past year, and sliders have said that the flow out of Curve 8 and into 9 is going more smoothly than at past World Cup events and testing weeks in Pyeongchang.

But as West learned, it’s still a very slippery slope. His Olympics aren’t over – he’s in 18th place, and he’s back on the ice for a third and fourth heat on Sunday. And he still has a shot of being the men’s slider on the team relay entry for the U.S. later in the games.

“To put it in the simplest terms, the curve’s just too long for how much pressure we have in there,” ”We lose pressure quickly, and that causes us to go sideways.”