The eighth seed, bidding to end a 23-year US men's major title drought, arrived in New York on the back of his Montreal victory and enjoyed strong backing in Arthur Ashe Stadium during the finely poised encounter.
"Super happy with the way the match went. I thought it was a battle to the end," said Shelton, who strained to hear an on-court reporter after the match. "If I was commentating, I would talk about how loud this crowd was from start to finish."
It looked as though it would be an easy day for Shelton after Hurkacz surrendered his serve with a pair of double faults in the sixth game.
But the Pole improved his level with 15 winners in the second set, where his forehand just kissed the baseline for the critical break on set point.
The pair battled toe-to-toe in a tense third set before Hurkacz gave it away in the tiebreak, letting Shelton get off to a costly 3-0 headstart.
The contest appeared to be heading towards a deciding set when Shelton was forced to defend two break points in the ninth game of the fourth set.
But the 2023 semi-finalist found another gear, hammering Hurkacz with his mighty forehand in the 12th game before flexing his arms in wide-eyed celebration as his opponent sent his forehand out on match point.
