The run, organized by the petrochemical company INEOS, featured a cycle of hype and commercial buildup more reminiscent of a heavyweight prizefight than a road race.

Organizers billed the two-hour mark as “the last barrier of modern athletics” and tried to get a hashtag, #nohumanislimited, trending on social media.

Kipchoge repeatedly compared a potential sub-two-hour marathon to humanity’s first journey onto the surface of the moon.

“The pressure was very big on my shoulders,” said Kipchoge, who revealed he had received a call from President Uhuru Kenyatta of Kenya the night before the run.

Whatever the scope of the achievement, it required a prodigious amount of planning.

Seeking the most welcoming environment for Kipchoge to attempt such a feat, the event’s organizers had settled on Vienna: It was not too warm, not too cold and not at all hilly. The altitude, 540 feet above sea level, was just right, and it was only one time zone away from Kipchoge’s training camp in Kaptagat, Kenya, where he had worked out for the past four months under the guidance of his longtime coach, Patrick Sang.

He had led a monastic existence there, eating, sleeping and exercising for the sole purpose of running fast. To his normal preparations he added workouts focused on core strength in order to lessen the strain on his hamstrings.

On Saturday, Kipchoge showed the subtlest signs of strain on his face in the first half of the run and fell a couple seconds behind his desired pace in a few portions. He ran the final stretches of the marathon with his lips curled into a gentle smile. Afterward, he walked with a barely perceptible limp.