How Coco Gauff’s new coach once helped Aryna Sabalenka fix her service woes
The US Open is just days away, though that has not stopped Coco Gauff from making a huge change in her coaching team.
World No 3 and two-time Grand Slam singles champion Gauff has reportedly parted ways with Matt Daly after a 10-month coaching partnership.
Under Daly’s guidance, the American won the China Open, WTA Finals, and French Open titles, with further finals reached in Madrid and Rome this spring.
However, recent months have seen a resurgence of the service struggles she initially hired Daly to help solve, with Gauff serving a career-high 23 double faults in a match at the Canadian Open this summer.
With Daly now out of her team, the 21-year-old is working with Gavin MacMillan, who, like her former coach, is a renowned grip specialist.
And, Gauff could take huge encouragement from the work that MacMillan did with one of her leading WTA rivals.
Who is Gavin MacMillan?
A former player himself, Canadian MacMillan has risen to prominence in recent years thanks to his work as a biomechanical coach.
In particular, it is his work with WTA world No 1 and three-time Grand Slam champion Aryna Sabalenka that has attracted the most attention and the most praise.
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Back in 2022, Sabalenka found herself in a similar position to rival Gauff, regularly hitting 10+ doubles faults during a match, and seemingly unable to solve her service woes.
It was a conversation with MacMillan during 2022 that helped the Belarusian begin to address the issue, starting at the 2022 Cincinnati Open.
“I called my wife and I talked it over, and then called them back and said: ‘Yeah’. So, I flew out there the next day. Saturday morning, we got to work,” revealed MacMillan to Talking Tennis last year.
“It was the phone call when I talked to her [Sabalenka] and said: ‘I understand this has got to be a really difficult time, but the thing I can promise you is that this isn’t mental, and if anybody is telling you that, just get up and walk away, and I can prove it. Your motion is so technically flawed – like I don’t know how you’re getting them in at all.’
“It’s just a testament to the fact that she’s [Sabalenka] pretty gifted, and finds a way, and you can see what ends up happening with the way these motions are taught by people, how these athletes are getting into this position.”
Immediately after beginning her work with MacMillan, Sabalenka would reach her second straight US Open semi-final, and finished as the WTA Finals runner-up in 2022.
However, she has since gone on to reach even greater heights.
Sabalenka is now a two-time Australian Open and one-time US Open champion, with a further three major finals to her name, and has now spent over 50 weeks as the WTA world No 1.
MacMillan was never officially her coach, though he remained as her technical coach and advisor for a lengthy period, helping power her success.
Gauff will now hope that the Canadian can have a similar impact on her game, with her double fault tally piling up in 2025.
The American has managed to achieve huge success this year, defeating Sabalenka in the French Open final, though she hit a combined 37 double faults across her first two Canadian Open matches in early August.
The 320 double faults hit by Gauff across 2025 are 109 more than any other player on the WTA Tour this season, though past coaching changes have brought initial success quite quickly for her.
Within two months of hiring Daly last Autumn, she triumphed at the WTA 1000 tournament in Beijing, before her triumph at the Year-End Championships in Riyadh.
Back in 2023, she won the Citi Open, Cincinnati Open, and US Open within weeks of hiring Brad Gilbert, whom she ultimately split with before hiring Daly after the 2024 US Open.
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