"I know," Stephens added, "there's going to be great things ahead for her."
With the Ashe roof shut during a heavy downpour — a tornado warning was in effect in the region — the thump-thump-thump of the rain created a bass beat that drowned out the usual sounds of a tennis match. It was so loud Stephens could barely hear the questions during her on-court interview.
Only one other court at Flushing Meadows can be covered during bad weather, but even that was an issue Wednesday evening, because wind helped push rain through the space between the concourse and the retractable cover at Louis Armstrong Stadium. So the match between two-time major finalist Kevin Anderson and Diego Schwartzman was delayed for nearly a half-hour at 5-all in the first set while workers used air blowers to dry the playing surface.
Scheduled for later in Armstrong was three-time Slam champ Angelique Kerber against Anhelina Kalinina, with the winner taking on Stephens. And last in Ashe was French Open runner-up Stefanos Tsitsipas against Adrian Mannarino, looking to join other men who moved on such as No. 2 Daniil Medvedev and No. 5 Andrey Rublev.
The conditions didn't matter at all to defending champion Naomi Osaka, who advanced earlier in the day when her second-round opponent, Olga Danilovic, pulled out of the tournament because of what she said was a viral illness — but not COVID-19.
Other past major title winners Simona Halep, Garbiñe Muguruza and Victoria Azarenka moved on more conventionally with straight-set wins. Muguruza next faces Azarenka, who in addition to a pair of Australian Open trophies is a three-time runner-up at the US Open, including when she lost to Osaka in the final a year ago.
Osaka hasn't been beaten in a Grand Slam match since losing to Gauff at the 2020 Australian Open.
And against Stephens, Gauff did briefly display the varied skills that helped her to that win and others on big stages, including twice against Venus Williams, and a run to the Roland Garros quarterfinals in June.
But Stephens, quite simply, was better. From 4-all at the outset, she claimed eight of the remaining 10 games, with a performance largely built with terrific placement of her serves and stinging forehands.
"The forehand," she said, "was key today."
Stephens, who was two points from losing to good friend Madison Keys on Monday in a rematch of their 2017 final in New York, won 39 of 49 points she served — an 80% rate — and saved the lone break point she faced.
More than a decade Gauff's senior at age 28, Stephens also handled her opponent's faster serves adroitly, breaking three times.
Both walloped the ball during big-strike exchanges from the baseline, with enviable and unrelenting power. The official stats showed they combined for 24 winners and 44 unforced errors, but that latter designation seemed unfair to assign, given how much each was forced to try to handle from the other side of the net.