Overheard at the Half-Marathon: ‘Wait, Was That Lil Nas X?’

Ahead of one of its signature events, New York Road Runners fielded an unusual email request on Friday night.

The rapper and singer Lil Nas X, who was visiting New York from Los Angeles, had seen some advertisements for the United Airlines NYC Half, a 13.1-mile race that was set to be staged on Sunday morning. And one of his representatives was curious: Did the race have room for one more runner?

“It kind of came out of the blue,” Rob Simmelkjaer, the chief executive of New York Road Runners, said in a telephone interview on Monday.

The nonprofit, which puts on about 60 races each year, including the New York City Marathon, was happy to oblige. It hardly mattered that Lil Nas X, who will turn 25 next month, had seldom run more than three miles consecutively, let alone a half-marathon. Or that he showed up for the race in a pair of Coach high-top sneakers, which are more boot than high-end racing flat.

Accompanied by Roberto Mandje, New York Road Runners’ senior adviser for running engagement and coaching, Lil Nas X was among more than 27,000 finishers, completing the race in 2 hours 32 minutes 53 seconds.

“We would be running and you’d hear someone shout, ‘Wait, was that Lil Nas X?’” Mr. Mandje said in an interview. “So he’d turn around and wave, and they’d freak out.”

Representatives for Lil Nas X did not respond to a request for comment.

Ahead of Sunday’s event, race officials kept his inclusion on the “down low,” Mr. Simmelkjaer said, as did Lil Nas X, who entered the race using his real name, Montero Hill. He also seemed determined to get the full experience, going so far as to visit the pre-race expo in person on Saturday to grab his race bib (No. 2271) and commemorative long-sleeve T-shirt.

He was wearing the shirt when he met up with Mr. Mandje on Sunday at 6:30 a.m. Mr. Mandje, who described himself as “one of the only people in the world” who was unfamiliar with Lil Nas X, did a quick assessment: Had he been training? (No.) Did he have a goal? (Finish.) Did he want to chat during the race? (Absolutely.) Above all, Mr. Mandje said, Lil Nas X wanted to enjoy the experience.

“We’re going to have a good time,” Mr. Mandje recalled telling him.

As Lil Nas X entered uncharted territory about halfway through the race, Mr. Mandje offered valuable perspective: Just about everyone else on the course had spent several months training for the race. Lil Nas X, in other words, was doing something — how to put it? — unconventional.

“I’m not sure everybody could pull that off,” Mr. Mandje said.

Lil Nas X’s footwear eventually caused some issues. Coach describes its high-top sneakers as “built for comfort and long wear.” But they are more than twice as heavy as a normal pair of running sneakers.

Sure enough, at around Mile 10, Lil Nas X told Mr. Mandje that his feet were bothering him. He even entertained the idea of momentarily stepping off the course so that he could buy a pair of running sneakers at a Foot Locker. But the store was closed, so he plowed ahead.

“Hey, you’ve made it this far,” Mr. Mandje recalled telling him.

Mr. Mandje also captured some behind-the-scenes moments on social media. At Mile 3, for example, he asked Lil Nas X how he was feeling.

“I feel nothing,” he said. “No pain at all. Nothing in my shoulders. Nothing in my legs at all.”

“And we’re learning a lot about running, right?” Mr. Mandje asked as they continued to jog.

“We’re learning a lot,” Lil Nas X said, “and I just lied about those things.”

At around Mile 4, when Mr. Mandje told him to wave goodbye to Brooklyn, Lil Nas X waved goodbye to Brooklyn. Lil Nas X provided additional insight at Mile 9: “I’m still alive.” And at Mile 11: “I smell ribs. I’m going to use that as motivation.” And at Mile 12: “It’s basically over with. I basically already did it.”

Mr. Simmelkjaer, who used the race’s live results app to track Lil Nas X’s progress, said he was impressed when the star ran through the finish line without any obvious signs of distress. After Mr. Simmelkjaer introduced himself, Lil Nas X grabbed a phone so that he could take several selfies with Mr. Simmelkjaer and his 15-year-old daughter, Julia.

“I’m officially no longer uncool as a dad,” Mr. Simmelkjaer said.

Mr. Mandje said he was left with the impression that Lil Nas X’s first road race would not be his last — “The seed is planted,” Mr. Mandje said — though that remains to be seen.

Lil Nas X celebrated his achievement on Instagram by posting a photo of himself with his finisher’s medal — from the comfort of a wheelchair.