NEW YORK – After double-faulting to fall behind two sets to none — a deficit he’s never overcome — in the second round of the U.S. Open on Thursday night, Carlos Alcaraz slung his equipment bag over a shoulder and trudged toward the locker room.

Glancing in the direction of his coach, 2003 French Open champion Juan Carlos Ferrero, Alcaraz pointed his right index finger at his temple, then wagged that finger, as if to say, “I’m not thinking straight.”

He might have been excused for being confused by what was transpiring under the closed retractable roof at Arthur Ashe Stadium on a chilly evening, and one set later, Alcaraz’s 15-match Grand Slam unbeaten streak was over with a sloppy 6-1, 7-5, 6-4 loss to 74th-ranked Botic van de Zandschulp.

“It was a fight against myself, in my mind, during the match. In tennis, you are playing against someone that wants the same as you — to win the match — and you have to be as … calm as you can, just to think better in the match and try to do good things,” Alcaraz said. “Today I was playing against the opponent, and I was playing against myself, in my mind. A lot of emotions that I couldn’t control.”

The result eliminated the pre-tournament men’s favorite and certainly was hard to predict beforehand, given the No. 3-seeded Alcaraz’s standing in the game, his excellence of late and his opponent’s far-lesser resume.