Yun's time: 1 minute, 40.35 seconds. Thousands of his countrymen showed up on Thursday morning to watch, and organizers expect even more on Friday when he will be the overwhelming favorite to emerge from the final two runs as a gold medalist.

"I think it would be more of a surprise if he didn't win a gold," US skeleton veteran John Daly said.

It was not a banner start for the US, which will need to seriously rally to reach the medal mix. Matt Antoine, the reigning Olympic bronze medalist, had a strong second run and will enter Friday in 11th place. Daly, back in his third Olympics after a brief retirement following a last-run debacle in Sochi, is tied for 13th.

"Second run was a lot better," Antoine said. "That's probably the best run I've had down the track. ... I proved to myself that I can put down the good runs. So two more clean, consistent runs and we'll see where that leaves me."Unless Yun makes a huge mistake, it's over. His margin over Tregubov is 0.74 seconds. That's a lifetime in sliding, especially when considering that the winning margin in the last four men's skeleton events at the Olympics is 1.21 seconds — combined.