Cole Hammer became the third-youngest player to ever qualify for the tournament.
This year's field contained 17 amateurs, the most since 1981. Fourteen of those qualified through various means last week.
After the first round of the US Open Hammer was tied for 135th place at 7-over, three shots better than Tiger Woods.
Cameras caught Hammer seemingly overwhelmed by the moment, crouched down, but, speaking after the game, he said: "I was just praying.
"I always pray right before my round on the first tee. And so, yeah, that's all I was doing," according to Business Insider UK.
"I wasn't emotional or anything... I don't even know, I mean, I've never felt that feeling, for sure, it was so different.
"But I liked it. It was kind of a different like kind of a sweet feeling to have. But, yeah, I can't even describe it."