Carlos Alcaraz conjured up what initially appeared — to the chair umpire, to everyone watching in the stands or on TV and to his opponent Ben Shelton — a remarkable lunging volley to win a point at the French Open on Sunday.

But Alcaraz knew it shouldn’t count. So after briefly thinking about it, the defending champion fessed up and called himself for breaking the rules, handing the point to Shelton during what would become a 7-6 (10-8) 6-3 4-6 6-4 victory for Alcaraz in the fourth round.

WATCH THE VIDEO ABOVE: Carlos Alcaraz’s rare sportsmanship wins over French Open.

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“It’s a shame, because it was the ‘Hot Shot’ of the day,” Alcaraz said later with a smile.

“Crazy shot,” Shelton said.

Early in the second set, Shelton whipped a passing shot well out of Alcaraz’s reach up at the net. So Alcaraz flung his racquet — and, as his equipment flipped through the air, its strings somehow not only made contact with the ball but sent it back over the net and onto the other side of the court.

Initially, the second-seeded Alcaraz was awarded the point. But he went over to the chair umpire to admit that he wasn’t holding his racquet when it touched the ball. That’s not allowed under the rules, so he personally conceded the point to Shelton.

When the official informed the Court Philippe-Chatrier crowd what had happened, Alcaraz was given a round of applause.

“I thought, ’OK, I could not say anything’. But I would have felt guilty if I didn’t say anything,” Alcaraz explained.

“It’s just about if I know that I didn’t (do), or I did, a wrong thing ... I have to say. I have to be honest with myself. I have to be honest with Ben, with everyone.

“It’s just about the respect we have against each other, and I think that sports, in general, should be like this.”

It came at what could have been a critical moment, because instead of leading 40-30 on his serve, Alcaraz was now down 30-40, giving Shelton his first break point of the match.

But Alcaraz saved that one — and five others in that 20-point game — along the way to taking a two-set lead in an entertaining matchup between a pair of 22-year-olds who hit the ball hard.

“I thought it was clean, you know? I thought he hit the volley, and (then) the racket flew out of his hand,” Shelton said.

“I was kind of surprised that he was, like, ‘No, I let go of the racquet and threw it’. Obviously a guy with a lot of sportsmanship.”

Shelton, an Australian Open semi-finalist earlier this year, delivered serves at up to 230km/h and forehands at up to 187km/h.

Alcaraz, already a four-time grand slam champion, showed off various parts of his repertoire.

It was tighter than the score might indicate: Shelton held three opportunities to own the opening set, leading in the tiebreaker at 6-4, 6-5 and 7-6. Take any of the subsequent points, and Shelton would own that set.

But Alcaraz — who meets No.12 Tommy Paul in the quarter-finals — saved the first with a service winner. Shelton netted a backhand on the next.

And the last ended with Shelton smacking a backhand right at the body of Alcaraz, who was up at the net and contorted himself in order to chop a drop volley winner.

Alcaraz then converted his second set point, closing a 15-stroke exchange with a down-the-line forehand that drew a mistake from Shelton.

The third set went to Shelton when Alcaraz put a forehand into the net, and the big-swinging American punched the air, then his chest, and screamed: “Let’s go, baby! Come on!”

The fourth swung Alcaraz’s way when he used a drop shot winner to set up a break point that he claimed for a 2-1 edge and, after a total of 3 hours, 19 minutes, he was able to finish off an 11th consecutive win at Roland Garros.