To experience a live-action viewing of Rafael Nadal is to be in awe of his sheer effort, the startling expenditure of unbridled energy, even as he fidgets in routinized preparation between points.

The first-timers in the stands are easy to find.

“Geez,” they cried during Nadal’s 6-2, 6-4, 6-1, 1-hour-41-minute pummeling of Alexandr Dolgopolov in the fourth round of the United States Open on Monday. “Whoa,” they exclaimed after another swashbuckling southpaw forehand accompanied by the guttural Nadal soundtrack and that familiar curled-lip sneer of momentary satisfaction.

The lower-bowl wonderment inside Arthur Ashe Stadium did not go undetected in the Nadal camp.

“I think the people from here love the fact that always Rafael gives whatever he has,” Toni Nadal, Nadal’s uncle and coach, said afterward. “He gives his body, his mind. We have made here good matches, and we have made here not-too-good matches. But always he has given whatever is possible, and I think this is the thing for life, not only in the tennis.”

Representing the climax of summer and the Grand Slam season, the Open can be a suspension from life, a two-week tennis barrage morning through late night.