After glimpses of revival in late 2024 and early 2025, Coco Gauff ’s serving demons have stormed back with fury. At the WTA 1000 Canadian Open in Montreal, she piled up 42 double faults in just three matches, nearly gifting away a set’s worth of points against Danielle Collins. Though her relentless fight carried her through, the warning signs blazed bright: without a stable serve, her ceiling remained capped. In response, Gauff cut ties with grip expert Matt Daly, hired after last year’s US Open , and turned to biomechanics guru Gavin MacMillan , the mastermind credited with rescuing Aryna Sabalenka’s once-broken serve. But who exactly is he?

Gavin MacMillan’s journey into the world of tennis and sports science is anything but ordinary. Growing up in Toronto, his earliest obses

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