It has been quite a run for the teenagers at the U.S. Open, especially a bright-eyed and beguiling troika that has managed to turn the Billie Jean King National Tennis Center into its personal playground.

Like young stockbrokers who have yet to see a bear market, Emma Raducanu, Leylah Fernandez and Carlos Alcaraz are experiencing the best of tennis life: match after match of effusive crowds that chant their names and ask for selfies, passing shots that nick the back of the line, and the freedom of swinging their rackets on a stage where they cannot lose, because no one was counting on them to win in the first place.