Coco Gauff’s serve is ‘biomechanically better’ as the real problem is revealed by legendary coach
Legendary coach Rick Macci has assessed that Coco Gauff’s serve has improved “biomechanically” despite the American star’s continued struggles.
Gauff hit the most double faults among all WTA Tour players in 2025 (431) and 2024 (430), and she also leads this unwanted statistic so far in 2026 with 103 double faults across her 14 matches.
The American star hired Gavin MacMillan, a biomechanics expert and coach, ahead of the US Open in August last year with the intention of solving her persistent problems with her serve.
The 21-year-old joined forces with MacMillan after parting ways with her previous coach Matt Daly, who had helped her win her second Grand Slam title at the 2025 French Open.
Macci, a former coach of Serena and Venus Williams, credited MacMillan for his work with Gauff while suggesting that the world No 4 should switch to a platform serve stance.
“Coco and her serve is biomechanically better. Gavin identified the real problems and I see it is stabilised,” Macci wrote on his X/Twitter account.
“But because she is double jointed and her wires are so free flowing she has more shake and bake that causes extra movements in the arm without trying.
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“I would go to a tight platform stance and put her on lockdown from the ground, be in a cylinder bubble and no more double.”
Speaking exclusively to Tennis365 last year, Macci predicted that Gauff would become world No 1 and reach “double digits” for Grand Slam titles if she improved her serve.
“I think not only could Coco become No 1 – which she probably will anyways – I think she could stay there for a long time, because her backbone is better than her backhand and she’s an Olympic sprinter with a racket in her hand,” said the American.
“She’s just such a great competitor, she checks all these other boxes. But when you’re out there double-faulting eight, 10, 12 times, or whatever, and you’re still winning, how good could you be when you’re only hitting a couple?
“I mean that’s like crazy. I mean, your mind has to be made of granite. I mean, a lot of girls would disappear into outer space. So I just have so much respect for Coco.
“But to be great, it’s a package, and if this serve could be modified, I have no doubt where she could end up – double digits (Grand Slams) is around the corner for Coco.”
