In a bold last-minute move, Coco Gauff–fresh off her French Open triumph and entering the US Open as the No. 3 seed–has parted ways with coach Matt Daly. In his place, she has turned to Gavin MacMillan, a biomechanics expert best known for helping Aryna Sabalenka transform her serve. Reports confirmed that MacMillan has already joined Gauff on site in New York, signaling an immediate shift in her preparation.
The Coaching Switch
Matt Daly, a grip technique specialist who joined Gauff’s team in late 2024, played a crucial role in her surge last season. Under his guidance, she won the China Open, the WTA Finals, and captured her second Grand Slam title at Roland Garros this summer. His focus on technical adjustments to her grip and serve brought early success, but recent months have exposed flaws that once again left Gauff vulnerable.
Enter MacMillan, the founder of Sport Science Lab, whose biomechanics-driven approach has been credited with reviving Aryna Sabalenka’s serve. His philosophy leans heavily on data, body mechanics, and video analysis–a scientific approach that could be exactly what Gauff needs to regain stability on one of the most important shots in tennis.
Why Now?
The decision comes at a low point in Gauff’s season. She currently leads the WTA in double faults and famously hit 23 in a single match against Danielle Collins earlier this summer. That weakness bled into her Wimbledon campaign and continued through the North American hard-court swing, leaving her frustrated and exposed in key moments.
The timing, just days before the US Open, has raised eyebrows. Former coach Rick Macci cautioned that instead of cutting ties, Gauff should have looked to expand her team with added science-based expertise. On the other hand, expert coach and ESPN analyst Darren Cahill has praised MacMillan’s methods on air on ESPN, suggesting the change could unlock new levels in Gauff’s game if she adapts quickly.
What It Means for Flushing Meadows
The move is undeniably risky, but it also highlights Gauff’s determination to solve her serve issues head-on. With a Grand Slam title already secured this season, expectations are sky-high. By choosing MacMillan, she is betting that science and biomechanics can turn her serve from liability to weapon on the sport’s biggest stage.
Whether this gamble pays off will become clear in the next two weeks. For Gauff, the US Open is no longer just about winning matches—it is about testing how quickly a bold coaching switch can reshape her future at the very top of the game.
Main Photo Credit: Susan Mullane-Imagn Images
