India, Sept. 9 -- Ben Shelton kept asking Carlos Alcaraz the same question through five sets of a bruising US Open quarter-final: how many times can you find another answer?

Alcaraz found one in the opening set. Shelton found several of his own after that. By the time the contest reached a deciding fifth set, neither had been able to shake the other off, with the match reduced to one final test of nerve after repeated swings in momentum.

Alcaraz took the opener 7-6(5), but Shelton responded emphatically, winning the second 6-1 and the third 6-3 before the Spaniard forced a decider by taking the fourth. What initially threatened to become another Alcaraz escape had instead developed into a sustained examination of his ability to absorb p...