Coco Gauff splits with key coach on eve of U.S. Open, practices with serve expert

Coco Gauff has split with a key coach on the eve of the U.S. Open.

Gauff, the world No. 3, has parted ways with grip expert Matt Daly, who she hired at the end of last year’s U.S. Open to strengthen her serve and forehand, two of the most important shots in tennis.

She has now brought on Gavin MacMillan, a biomechanics specialist who helped rescue world No. 1 Aryna Sabalenka’s serve. MacMillan was on court with Gauff during practice at the Billie Jean King Tennis Center Wednesday, alongside her longtime coach Jean-Christophe Faurel. Gauff hit on Arthur Ashe Stadium with Elina Svitolina, before doing serve practice with MacMillan and Faurel as rain fell on the outside practice courts in New York.

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A representative for Gauff confirmed the change, first reported by ESPN. MacMillan was not immediately available for comment.

After a period of upturn in late 2024 and early 2025, Gauff’s serving troubles have returned. She hit 42 double faults in three matches during the WTA 1000 Canadian Open in Montreal, one rung below a Grand Slam. In one match against Danielle Collins, Gauff double-faulted away almost a set’s worth of points. She won that match, through the tenacity and ability to get every ball back that is one of the bedrocks of her game. But it was clear to her that her prospects were limited as long as she could not consistently land a quality first or second serve.

After losing to Victoria Mboko in Canada, she then hit 16 double faults in a quarterfinal defeat to Jasmine Paolini at the Cincinnati Open.

Gauff has consulted with Andy Roddick, who has tried to get her to adjust her toss. She worked with Daly, who is a grip specialist, who altered how she held the racket. MacMillan will likely pursue a more substantial breakdown of the motion, but whether or not Gauff can make those changes in real time as she tries to get through the draw of the year’s final Grand Slam is another question.

Jason Stacy, one of Sabalenka’s lead coaches, brought in MacMillan in summer 2022 to fix a serve that was producing more than 20 double faults in matches. He got immediate results, as Sabalenka’s double faults plummeted and she reached the semifinals of that year’s U.S. Open. She has since gone on to win three majors on her route to the top ranking in women’s tennis.

Gauff has also proven deft at adapting to new ideas in the past. She won the U.S. Open in 2023 less than two months after she brought on Brad Gilbert. She won the China Open in Beijing and the WTA Tour Finals in Riyadh just weeks after bringing on Daly last year. But strings of double faults have defined the tougher moments of her career.

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It was last year’s U.S. Open exit to compatriot Emma Navarro, which also featured a string of double faults, that led Gauff to say that she didn’t want to lose that way any longer. She fired coach Brad Gilbert, with whom she had won the title in New York in 2023, and brought in Daly. The partnership seemed to work, but the results have not held of late.

The U.S. Open singles main draws begin Sunday Aug. 24.

(Photo of Coco Gauff: Daniel Kopatsch / Getty Images)

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