Coco Gauff's decision to part ways with coach Matt Daly and replace him with a renowned biomechanics expert ahead of the 2025 US Open was recently assessed by prominent tennis insider Gill Gross. According to Gross, the significant decision made by the two-time singles Major champion increases her chances of winning the hardcourt Major, albeit by a small margin.Following her title triumph at this year's French Open, Gauff has so far endured a forgettable summer swing. She lost both of the matches she played on grass, including her first-round match at the Wimbledon Championships. She hasn't fared much better in the North American summer hardcourt swing either, with her losses marred by a shockingly high number of unforced errors, including numerous double faults stemming from a rushed second serve.In a bid to challenge for the women's singles title at the 2025 US Open, Coco Gauff replaced Daly with biomechanics expert Gavin MacMillan, who most notably helped reigning No. 1 Aryna Sabalenka get over her second serve troubles. Tennis insider Gill Gross recently shared a video on his Instagram, in which he delivered his verdict on the WTA No. 3's collaboration with MacMillan. Gross said:"I think that her chances of winning the US Open may still be relatively small for a top five player who's already won a Major this year. In my view, they've gone up. Is it scary to make a technical change, potentially some drastic ones this close to the start of a Major? Absolutely. Does it go against conventional wisdom to do so? Yes it does."The insider went on to highlight Gauff's recent struggles with both her first and second serves. Gross opined that had the 21-year-old not made a change, there would be no way for her to challenge for the women's singles title at Flushing Meadows considering the flaws in her game. Gross added:"But if you look at where she's been at all summer long since the Roland Garros title in all of her losses first serve percentage under 55%, double fault rates between 10 and 20%. She had no chance at this year's US Open if she didn't do something drastic, if she didn't do something bold, and I don't think it can get much worse as far as the serve is concerned than what it has been all summer long." View this post on Instagram Instagram PostCoco Gauff to begin US Open 2025 campaign with 1R clash against unseeded Australian who put an end to Serena Williams' illustrious careerCoco Gauff hits a forehand during a practice session at the 2025 US Open (Source: Getty)Coco Gauff, seeded No. 3 in the women's singles main draw at the 2025 US Open, is set to kickstart her campaign at the hardcourt Major with a first-round clash against Ajla Tomljanovic. The Australian, ranked No. 84 in the world as of now, infamously engineered the legendary Serena Williams' exit from the 2022 US Open, marking the end of the American's stellar tennis-playing career.On paper, Coco Gauff, who won the New York Major two years ago, is the favorite to come out on top against Tomljanovic. The pair has clashed on just one previous occasion, and that particular encounter ended in the American's favor.