SPOTTED: Coco Gauff training with biomechanic coach Gavin MacMillan at US Open

MacMillan helped rework the serve of world No. 1 Aryna Sabalenka.



© Matt Fitzgerald

NEW YORK—Coco Gauff appears to be experimenting with her team composition ahead of the 2025 US Open, the world No. 3 seen training with biomechanic coach Gavin MacMillan on Wednesday.

MacMillan is the technician behind the reworked serve of Aryna Sabalenka, who won her first Grand Slam title six months into their partnership.

Gauff was also seen working with longtime coach John-Christophe “JC” Faurel, who first joined her team in 2019. According to a report from Bounces, Gauff has split from coach Matt Daly.

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“Only have good things to say about Coco, enjoyed working with her,” Daly confirmed to Bounces.

A former coach of ATP former No. 10 Denis Shapovalov, Daly first came on board Team Gauff last fall. Gauff went on to win titles at the China Open and the WTA Finals in Riyadh.

Since winning her second Grand Slam title at Roland Garros, Gauff has posted a 5-4 win-loss record, struggling with her serve through losses in the first round of Wimbledon and the quarterfinals of the Cincinnati Open.

Gauff is set to be the No. 3 seed at the US Open after dropping from No. 2 as a result of Iga Swiatek’s win in Cincinnati, meaning she could face Sabalenka or Swiatek in the semifinals.