Coco Gauff left the 2025 US Open with mixed emotions: bruised after a loss to Naomi Osaka but upbeat about the work she has started on her serve. Observers had noted a sombre demeanour during parts of her run in New York, yet Gauff framed the week as part of a broader process.

The changes began after a difficult 2024 North American hard-court swing. She parted ways with Brad Gilbert and joined Matt Daly last September, a partnership that produced immediate results: she won the China Open and finished the year with the season-ending WTA Finals trophy. Her form carried into 2025 with a second major at Roland Garros and runner-up finishes at the Madrid Open and Italian Open, but she acknowledged a persistent weakness in her serve.

When Gavin MacMillan became available after the Cincinnati Open, Gauff made another significant switch. She and MacMillan focused on biomechanics and decided to change her entire service motion. That overhaul left the build-up to the US Open difficult; she described shoulder pain after practice but accepted the short-term discomfort.

A testing three-set win over Ajla Tomljanovic opened her campaign. There were tears during and after a two-set victory over Donna Vekic, and she dropped only four games against Magdalena Fręch in the third round before the defeat to Osaka. After the Fręch match she admitted she “broke down.”

She detailed the emotional swing: “I think that trying to be more positive after the match, I was really disappointed,” she admitted. “Kind of broke down to my team and then hearing their perspectives and everything, it definitely is a lot of positive things.

“If I think if I kept the way I was going in Cincinnati to here, I would have been out the first round. And so I think that where my serve started from the start of the tournament to today was a big improvement. And I feel like now I just have to get everything to work together. But, yeah, I knew going in it was going to be a tough tournament for me.”

Statistically there are signs of progress: she served 320 double faults before the US Open, added 23 in her first three matches in New York and five more against Osaka. “My goal going into the tournament this year was not to lose the same way that I lost last year. And I don’t remember how many doubles I hit in my match against Emma, but it was definitely in the double digits, so I didn’t do that today,” she said.

At 21 she already owns 10 WTA Tour singles titles, including two Grand Slams, a WTA Finals trophy and two WTA 1000 titles, and she has peaked at No 2. With older rivals such as Aryna Sabalenka, 27, and Iga Swiatek, 24, she sees room to grow: “So I think for me, it just gets me excited to realise if I have, like, four more years of just working as hard as I am right now and actually doing the right things, like where my game could be.”

Naomi Osaka credited a shift in approach and clear coaching direction for a commanding straight-sets victory over No. 3 seed Coco Gauff at the US Open, 6-3, 6-2. Hired a little more than a month ago, Tomasz Wiktorowski has already altered Osaka’s match management more than her stroke production.

“I think when I was searching for a new coach, I just wanted someone with a lot of knowledge,” she says. “I don’t really like questioning if someone really knows what they’re talking about.”

Wiktorowski, who helped guide Iga Swiatek to the No. 1 ranking and five of her six Grand Slam titles, has focused on placement and patience. Osaka described a different sideline presence than she expected. “When he smiles, he really is like a teddy bear,” Osaka says. “I feel like it kind of creates a safe space for me to be able to express myself and my tennis.”

Those small adjustments produced immediate results. In Montreal, their first event together, Osaka reached her first top-tier final since 2022. At the US Open, she advanced to her first Grand Slam quarterfinal since 2021 after a measured performance against Gauff.

“He’s done a lot in my game in a very short amount of time that have been really simple fixes, but they’ve just also been kind of mind-blowing at the same time,” she says of Witkorowski. “[He] has talked to me a lot about the placement of my shots and not necessarily going for winners most of the time.”

Osaka finished with 10 winners and 12 unforced errors. Gauff committed 33 unforced errors, the same number of points she won. Osaka made 42 percent of her first serves and did not face a break point. She also highlighted improved defense and court coverage. “I might do something stupid once I do get to the drop shot, but I get there.”

“I think I played smart,” she said. “I feel like Tomasz gave me a game plan, and I executed it pretty well. All credit to him. It was just very clear for me what I had to do from the beginning. If I stepped outside of those lines, it was very easy to go back in them.”

“She forced me to earn every point out there today,” Gauff said of Osaka. Osaka added: “I think that says a lot for me to be completely fine with playing long rallies with her, and just knowing that I’m OK not going for anything until I get my, like, perfect opportunity.” “Part of my plan was just not to, like, freak out when she gets a lot of balls back and just keep building the point,” Osaka said.

Naomi Osaka defeated Coco Gauff 6-3, 6-2 at the US Open, a result that prompted blunt assessment from Tim Henman about Gauff’s current state. Osaka dominated her service games, losing just six points on serve in the entire match. Gauff’s campaign at the event ended in straight sets.

Gauff struggled with a fragile serve and inconsistent groundstrokes while committing 33 unforced errors, a combination that left little chance against an opponent playing with clarity. Her body language during the match suggested she lacked belief she could compete with Osaka.

Henman was direct in his diagnosis. “When you talk about someone being in the zone, that’s when you’ve got that really clear mindset and Osaka had that,” Henman told Sky Sports.

“When you think about the other end of the court with Gauff it just looks like she’s so confused out there.

“It’s so stressful. She’s focusing so much on her serve, as we all are, when you’ve got that type of mindset, it’s very difficult to play your best tennis, especially against a world-class player who is making life difficult for you.

“Gauff is such a good competitor, but you saw at the end of the match that she couldn’t wait to get off that court quick enough. We’ve seen the emotion on the court, in tears at times. It’s been almost traumatic at times.

“She needs a little bit of time away from this environment to decompress and contemplate her next move.”

Gauff addressed the match in her press conference. “Today was disappointing because I felt it was the best I’ve served through the whole tournament,” she said. “Off the ground, I made too many mistakes in too many areas. So it was kind of a weird match with the different areas swapping.

“With how emotional this week way, I was maybe a little empty out there today.”

She added serving biomechanics expert Gavin MacMillan to her team shortly before the US Open and accepted that attempting to rebuild her serve so close to a Grand Slam proved difficult. Having won the French Open title in June, Gauff now has time to work with MacMillan, and Henman suggested a period away from competition may help her reshape the serve and return with a more complete game after a challenging few months since Roland Garros.