At the end, when five riveting sets and one agonizingly tight tiebreak were over — and when the latest-finishing match in U.S. Open history had concluded — Ben Shelton was not the only player smiling. Carlos Alcaraz, the player Shelton had just defeated in an entertaining, spine-tingling marathon, was smiling too. The dethroned defending champ grinned as he walked to the net to hug Shelton.