The mindset at the service line, in Gauff’s own words, has flipped.

“I’m now serving and it’s ‘Oh, I’m going for the ace,’ or ‘I know I can hit the serve,'” she told reporters in New York, before contrasting it with a year earlier when she was thinking “I hope I make it in.”

That confidence carried her through a 6-3, 6-4 first-round win over world No. 53 Zeynep Sonmez on Tuesday night, an 80-minute contest under the closed roof of Arthur Ashe Stadium that briefly wobbled when Sonmez broke back to level the second set at 3-3, before Gauff broke again on a Sonmez double fault and closed it out.

“I was just trying not to panic. She started coming to the net and playing great tennis,” Gauff said of the second-set dip.

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A year rebuilding with MacMillan

Gauff added the Canadian biomechanics coach Gavin MacMillan to her team ahead of last year’s US Open, pairing him with longtime coach Jean-Christophe Faurel. MacMillan, best known for helping repair Aryna Sabalenka’s serve, has spent the past twelve months reworking Gauff’s serve mechanics alongside Faurel.

She said the first weeks were slow going and that the outside noise was heavy.

“Last year I knew all eyes were going to be on the serve. Gavin is so great at what he does, so I felt a lot of pressure.”

“It didn’t really show within the first two weeks, which is normal.”

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The fix, in her telling, was repetition before power.

“It was about making it consistent. Once I got confident in the consistency, then I was able to pull the trigger a lot more often.”

Cincinnati title, and the ranking math in New York

The overhaul has already turned into silverware. Gauff won the Cincinnati WTA 1000 title in August, echoing the 2023 run at the same event that preceded her first US Open crown.

The ranking picture at Flushing Meadows is tighter. Aryna Sabalenka is chasing a 100th consecutive week at world No. 1, she will have spent 99 straight weeks on top by the end of the tournament, and the WTA has set out the scenarios that decide who leaves New York on top: Sabalenka keeps the ranking only if she wins the title and No. 2 Elena Rybakina loses before the semifinals; Rybakina takes over the moment she reaches the last four, regardless of any other result; and Gauff needs both a US Open title AND a Rybakina exit before the semifinals to become world No. 1 for the first time.

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Gauff’s second-round opponent will be the winner of Paula Badosa versus Daria Kasatkina, a match suspended by rain with Badosa leading 6-1, 1-2.

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