WHAT HAPPENED: In a first-round blockbuster featuring two of the more promising young performers on the American tennis landscape, No. 26 seed Jack Sock turned back an upset bid from on-the-rise 18-year-old Taylor Fritz, 7-6, 7-5, 3-6, 1-6, 6-4, in Louis Armstrong Stadium.

It marked the second time this year that the countrymen went the distance at a Grand Slam, the 23-year-old Sock claiming another opening-round encounter, 6-4, 3-6, 0-6, 6-3, 6-4, at the Australian Open in January.

“Taylor turned pro last year, and he’s top 60 now for a reason,” said Sock, who totaled 19 aces and 58 winners in earning the victory. “He’s an incredible young player, and he has a bright future in front of him. But I was able to scrap out a few points in the end.”

The evenly contested first set (each player registered 15 winners to 12 unforced errors in the stanza) came down to a tiebreak, Sock often punctuating points with his punishing forehand en route to a 7-3 finish. With Fritz serving to stay in the second set down 5-6, 30-40, Sock lured the Californian into the net and forced an errant volley to claim what appeared to be a commanding two-set lead.

But Fritz wasn’t finished just yet. With veteran cool, he held his ground, and as the unforced errors began to mount for Sock (he amassed 73 in all, including 17 double faults), the David Nainkin and Christian Groh-coached wunderkind not so quietly worked his way back into the match. A pair of service breaks put him on the scoreboard in the third set, and he simply steamrolled through the fourth to even the match at two sets apiece.

Making his first appearance since claiming the mixed doubles gold and men’s doubles bronze in Rio, Sock would strike first in the telltale fifth with breaks in the second and fourth games to surge ahead 4-0. With Fritz serving down 2-5, Sock slipped and fell to the court while chasing a groundstroke, bloodying his knuckles in the process. But the brief scare didn’t keep him from closing out the match in three hours, 20 minutes.

“I slipped on the line,” he said. “This court is pretty quick. I got it pretty good, but I’ll tape it up, and it’ll be ready to go in a couple of days.”

Fritz, who registered 41 winners to 42 unforced errors, has now lost 12 straight matches against Top 60 opponents since beating No. 30 Jeremy Chardy in Acapulco. 

WHAT IT MEANS: You’ve come a long way, kid. This time last year, Fritz was ranked No. 685 in the world, a fresh-faced power-baller with oodles of upside but still a long road ahead of him if he wanted to be considered among the greats that his homeland has historically churned out over the years.   

By the time he left Flushing Meadows, the Californian had a US Open junior title to his credit and, perhaps more importantly, a newfound confidence, a belief that he did indeed belong at the elite level. He responded by reeling off a pair of USTA Pro Circuit titles in the fall and in 2016 took it a step further, reaching his first ATP World Tour final in Memphis, becoming the youngest American in an ATP final since a 17-year-old Michael Chang won Wembley in 1989. He arrived in New York earlier this month on the cusp of the Top 50, at a career-high No. 53 — the youngest member of the Top 100.

A 632-spot jump in one year? Not bad.

Fritz’s rise, as well as the progress made by countrymen Tommy Paul, Reilly Opelka, Frances Tiafoe and Jared Donaldson, even caught the attention of one Roger Federer, he of a record 17 Slam titles.

“I've seen the Americans really making their move,” observed the Swiss.

Fritz’s ability to push Sock to five sets on two occasions shows that he’s only getting closer. If he keeps progressing the way he has over the past year, the sky’s the limit.  

QUESTION: Sock was the only player — man or woman — to win two tennis medals in Rio, a career highlight for sure. But is he ready to break through at the majors, where he has yet to advance beyond the fourth round?