In Las Vegas, the house always wins. And in Tuesday’s head-to-head rollerski race between Marcus Hellner and Petter Northug, Northug was the house. On a course laid out by his Norwegian magazine sponsor—and modified at the last minute to give him a better shot at the win—Northug took the last two heats of a best-of-three series in the parking lot of the Palms Casino, evening the score with Hellner after losing to the Swede in...