NEW YORK — When you hear a line judge with stout lungs yell, “Fault!” at 1:06 a.m., and his voice echoes through the stadium as if across a barren mountainside, you know your life might just be misspent.

Moments earlier, Anderson had served to stay in the fourth set at 5-6, and the sparse crowd had risen and marshaled its scattered throats, trying to encourage Querrey to deepen the American wave here.

When their sound died down, and the last strains of it rang out somewhere in the rafters under the closed roof, Anderson blasted a 121-mph serve into the corner, and it caromed off Querrey’s racket frame and straight to the ground.

He gave a thoughtful explanation of how Anderson-Querrey matches hinge on little twists here and there — they played five sets on a gnarled court at Wimbledon — and so he concluded, “It felt fantastic seeing that last ball go long.”

That’s because it’s a physical sport, he said, so he doesn’t get “tired.” Counterintuitively, for these record-threatening matches, it’s more tiring to sit sedentarily and eat a giant chocolate-chip cookie while noticing four jumpy lads across the aisle and wondering if they might have school in five hours.