Coco Gauff has advanced to the third round of the 2026 US Open after defeating Paula Badosa 6-4, 7-6(5) at Arthur Ashe Stadium on September 3. The biggest change Gauff has identified in her game is the gradual improvement of her serve, particularly her confidence in committing to it rather than worrying about simply getting the ball into play.

That development is especially important after Gauff struggled with double faults and serve consistency during 2025. She has worked with biomechanics expert Gavin MacMillan and says the difference in her serve and mindset is now significant compared with last year.

Introduction

Coco Gauff is into the third round of the 2026 US Open, but the result is only part of the story.

The fourth-seeded American defeated Paula Badosa 6-4, 7-6(5) on Thursday night at Arthur Ashe Stadium, ending a difficult recent run against the Spaniard and securing a place in the third round for the fifth consecutive year.

The bigger development has been the evolution of Gauff's serve.

After spending much of 2025 battling inconsistency on that shot, Gauff entered this year's tournament with noticeably greater confidence. She has described the change as gradual, saying repeated technical reminders from her coaching team have allowed her service motion to develop naturally.

That improvement was already visible before the US Open and has become one of the defining features of her current form.

What Happened?

Gauff's latest victory came against a particularly difficult opponent.

Badosa entered the match with a 5-3 career advantage over Gauff and had won their previous two meetings, including a comeback victory over the American in Berlin earlier this year. Despite those recent results, Gauff controlled the key moments in New York.

The first set remained competitive until Gauff broke Badosa while the Spaniard was serving at 3-3. Gauff protected that advantage to take the opening set 6-4.

The second set was even tighter. Neither player could create a decisive separation, forcing a tiebreak. Gauff eventually prevailed 7-5 to complete the straight-sets victory.

For Gauff, the victory was more than simply another step through the draw.

She said the match was the kind of challenge she needed to build confidence, particularly against a former world No. 2 and strong competitor such as Badosa.

Key Details

The main facts from Gauff's second-round victory include:

• Opponent: Paula Badosa of Spain
• Result: Gauff won 6-4, 7-6(5)
• Venue: Arthur Ashe Stadium, New York
• Date: September 3, 2026
• Seed: No. 4
• US Open progress: Third round
• Third-round opponent: Cristina Bucsa of Spain
• Head-to-head against Badosa: Badosa still leads 5-4
• Consecutive US Open third-round appearances: Five
• Current form: Gauff entered New York after winning the Cincinnati Open

The victory also extended Gauff's strong run of form. She had won the Cincinnati title immediately before the US Open, defeating Jessica Pegula in the final.

Background: Why Gauff's Serve Has Become So Important

The serve has been one of the most closely watched parts of Gauff's game over the past two seasons.

Her athleticism, speed and return game have long been among her biggest strengths. But inconsistent serving created problems during 2024 and 2025.

At the 2024 US Open, she hit 19 double faults during her fourth-round loss to Emma Navarro. The following season was even more difficult: the official US Open website reported that Gauff recorded 431 double faults in 2025, 130 more than any other woman on tour.

Rather than simply trying to avoid mistakes, Gauff and her team began working on the mechanics of the serve.

She brought biomechanics expert Gavin MacMillan onto her team ahead of the 2025 US Open. MacMillan had previously worked with Aryna Sabalenka.

The improvement did not happen overnight.

Gauff acknowledged that the changes initially came with pressure because she knew the serve would receive significant attention. But by 2026, she said her mindset had changed from hoping to get the serve in to believing she could use it aggressively.

That psychological difference may be as important as the technical adjustment itself.

The Biggest Change in Coco Gauff's Game

Gauff has identified her serve and her confidence in the serve as the biggest change.

Before the US Open, she explained that she did not immediately notice how different her service motion looked. It was only after seeing video comparisons that she recognized the extent of the technical change.

The improvement has been gradual rather than the result of one dramatic mechanical adjustment.

Her coaches have continued giving her reminders, and those changes have slowly become part of her natural motion.

The most important development is that Gauff now feels more comfortable taking the risk of attacking with the serve.

That matters because an uncertain first serve can affect an entire game. When a player is worried about double faults, the hesitation can influence both first- and second-serve decisions. Greater confidence allows Gauff to swing more freely.

The Numbers Show the Progress

The improvement is not only about how Gauff feels.

WTA statistics show that Gauff entered the US Open with a 69.7% service-games-won rate in 2026, compared with 68.8% in 2025. Her 2026 figures also showed improvements in several serving categories compared with the previous season.

At the start of the tournament, the results were encouraging.

Against Zeynep Sonmez in the first round, Gauff won 6-3, 6-4 and produced five aces and 22 unreturned serves. She also won 64% of her second-serve points and saved four of five break points.

Those statistics are particularly significant because Gauff's second serve has historically been an area opponents have tried to attack.

A more reliable serve gives her another way to control points before her elite movement and return game become decisive.

What Officials / Organizations Said

The official US Open coverage has highlighted Gauff's improved serving as one of the central stories of her 2026 campaign.

The tournament's report on her first-round victory noted that her serve held up particularly well during pressure points. Gauff saved three break points in a lengthy game while Sonmez was leading 3-2 in the second set before closing out the match.

Gauff herself has emphasized that the changes have been gradual.

She has also stressed that she does not need the serve to be perfect. Her focus is increasingly on getting the motion consistent enough that she can commit to the shot.

That mindset represents a major contrast with the uncertainty she experienced during the previous US Open.

Why This Matters

Gauff already possesses one of the strongest return games in women's tennis.

The official US Open analysis noted that she ranked third in return games won among women who had played at least 20 tour matches, behind Iga Swiatek and Marta Kostyuk.

That creates an important combination.

If Gauff can consistently hold serve while continuing to put pressure on opponents' service games, she does not need to dominate every rally to win matches.

The improvement also changes the way opponents may approach her.

Previously, serving issues could provide a clear tactical target. A more dependable serve reduces that vulnerability and makes Gauff's overall game harder to disrupt.

Her recent results suggest the change is arriving at an important time. She won Cincinnati before arriving in New York and has now defeated Sonmez and Badosa without dropping a set.

What Happens Next?

Gauff will face Cristina Bucsa in the third round on Saturday.

Bucsa is another Spanish opponent, meaning Gauff will face another player from the same country immediately after defeating Badosa. The third-round meeting is confirmed by the WTA's tournament coverage.

Gauff enters that match with momentum and a serve that appears significantly more reliable than it was a year ago.

However, two rounds are still a long way from another US Open title.

The 2023 champion's immediate challenge will be maintaining the same discipline that helped her overcome Badosa. If the serve remains dependable and her return game continues to produce pressure, Gauff will have a strong platform for another deep run in New York.

The biggest change may ultimately be less about the speed of her serve and more about how comfortable she is trusting it.

FAQs

What is the biggest change in Coco Gauff's game?

The biggest recent change is the improvement in her serve, along with greater confidence in using it aggressively. Gauff has said the transformation has happened gradually through technical work and repeated coaching reminders.

Did Coco Gauff reach the third round of the 2026 US Open?

Yes. Gauff defeated Paula Badosa 6-4, 7-6(5) on September 3 to reach the third round. It is her fifth consecutive appearance in the US Open third round.

Who will Coco Gauff play in the third round?

Gauff will play Cristina Bucsa of Spain in the third round.

What was Coco Gauff's score against Paula Badosa?

Gauff defeated Badosa 6-4, 7-6(5) at Arthur Ashe Stadium.

Why was Gauff's serve a concern?

Gauff experienced significant serving inconsistency during 2024 and 2025, including a high number of double faults. The US Open reported that she recorded 431 double faults during the 2025 season.

Who helped Coco Gauff improve her serve?

Gauff worked with biomechanics expert Gavin MacMillan, who joined her team ahead of the 2025 US Open. MacMillan had previously worked with Aryna Sabalenka.

Did Coco Gauff win a tournament before the US Open?

Yes. Gauff won the 2026 Cincinnati Open, defeating Jessica Pegula 6-2, 6-4 in the final. The victory was an important part of her strong preparation for the US Open.

Is Coco Gauff the 2026 US Open defending champion?

No. Gauff won the US Open in 2023. She is seeking a second title in New York in 2026. The 2025 US Open ended with Gauff reaching the fourth round, where she lost to Naomi Osaka.

Sources

• US Open — Official tournament coverage: Gauff's 2026 US Open turnaround and serving improvements.
• US Open — Official match report: Gauff's 6-4, 7-6(5) victory over Paula Badosa and third-round qualification.
• WTA — Official match report: Gauff's victory over Badosa and upcoming match against Cristina Bucsa.
• WTA — Official player/match statistics: Gauff's 2026 serving and career statistics.
• WTA — Official report on Gauff's serving: Details of the revamped serve and her changing mindset.
• Reuters — US Open Day Five: Confirmation of Gauff's progression alongside other major tournament results.
• Associated Press / People: Additional context on Gauff's recent work on her serve and mental approach.