Coco Gauff has played around 47 matches this season, but surprisingly, she has committed 320 doubles faults so far. At the Canadian Open, we saw her commit 42 doubles faults, and guess what? 23 of those came in a single match (R64 against Danielle Collins)! If we take a look at her performance in the Cincinnati Open, although she kept it tidy in her first two matches, Gauff committed 16 double faults in her QF match against Jasmine Paolini. These staggering numbers have made Gauff one of the most error-prone servers on Tour.

A few weeks ago, while addressing these issues in an interview with Tennis 365, Serena Williams’ ex-coach, Rick Macci, expressed her interest in working with Gauff. He said, “This has to be science-based, and it has to be done from a biomechanical point of view.” Having said that, Macci also mentioned that he would work closely with Dr. Brian Gorden, who has a PhD in Biomechanics, and look to modify Coco Gauff’s technique. According to Macci, Gauff’s serving woes can be fixed in an hour. Recently, as per ESPN’s reports, Gauff parted ways with her coach Matthew Daly and brought in biomechanics specialist Gavin MacMilan to her team. According to several reports, MacMilan will be working alongside her longtime coach, Jean-Christophe Faurel.

Although Coco Gauff didn’t release a public statement, in a recent interaction with renowned tennis journalist Ben Rothenberg on Bounces, Matt Daly confirmed that the decision had happened “recently“. However, when asked to share his thoughts on this split, he added, “Only have good things to say about Coco, enjoyed working with her.”

Coco Gauff brought Matt Daly into her team after her shocking exit from last year’s US Open at the hands of Emma Navarro. He replaced Brad Gilbert with Daly at that time. Following his inclusion in the team, the duo immediately found success at the China Open and the WTA Finals. In 2025, Daly helped her clinch the French Open title. If we go by the numbers, under him, Coco Gauff played 17 WTA tournaments and won four out of them, including the Roland Garros triumph.

Following his departure, Gauff was spotted practicing with her new team in NY. As per the reports, MacMillan, who had previously helped Aryna Sabalenka improve her serves, was spotted paying special attention to Coco Gauff’s serve and forehand.

A sudden dip in performance is a big worrying factor for Gauff ahead of the US Open, but how crucial can this change be in terms of overcoming her serving woes?

Rick Macci praises the bold call by Coco Gauff ahead of the 2025 US Open

This year, Coco Gauff has a win-loss record of 35-12, but she has won just 1 title as of now. Other than winning the title at Roland Garros, Gauff came closer to lifting the titles on many occasions. At some of the tournaments, she even started as a favorite, but her excessive errors deprived her of title triumphs. Seeing her bring in a biomechanics specialist (Gavin MacMillan) to the team, Rick Macci shared his thoughts on the same.

He tweeted, “Corey Gauff just made the best decision in his life for Coco [Gauff]. By hiring Gavin MacMillan, this can be solved real quick and make her serve click. What she hears will be 100% different from anything in the past. He knows the issue and understands joint angles and soft tissue. Career changer! This is not only a game changer for Coco hiring Gavin MacMillan, but a major league career changer.” He also highlighted the changes that Sabalenka had made with the help of MacMillan. Aryna Sabalenka also had a severe issue with her serve a few years ago, but her constant effort alongside Gavin MacMillan turned things around for her later on.

Rick Macci believes Coco Gauff will go to “another level” because of Gavin MacMillan. Does he consider her a favorite at the 2025 US Open, though? Surprisingly, Macci snubbed both Gauff and Sabalenka to pick Mirra Andreeva as the favorite for the US Open. “I called this a couple of years ago. I knew where this was going. She (Andreeva) is gonna be number one, she’s my pick to win the US Open,” he said in a recent interview with Tennis 365. How far do you think, though, Gauff can reach at this year’s US Open? For live, minute-by-minute coverage of the US Open, head to our Live Blog.