PYEONGCHANG - Yun Sung-bin has spent thousands of hours at the sliding track his nation built for the Pyeongchang Olympics, studying every nuance and scrutinizing every inch.

He knows it better than anyone alive.

And the payoff for that work is potentially two runs away.

South Korea has never been close to an Olympic medal in any sliding sport, and Yun — the one his nation identified as the slider with the most potential of becoming a star at the games — is expected to change all that. He emerged from Thursday's first two runs of the men's skeleton competition with a huge lead over Nikita Tregubov, one of the Olympic Athletes from Russia.

"I didn't show 100 percent, so I will show 100 percent (Friday)," Yun said.