NEW YORK — Coco Gauff talked at length about the improvements made to her serve and mentality coming into the US Open, and both were on display midway through the second set of her opener against Zeynep Sonmez.

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In front of a packed house at Arthur Ashe Stadium on Tuesday night, Gauff saved three break points in a six-deuce game spanning nine minutes to hold for 3-3. The World No. 4 then proceeded to finish the match with authority, closing out a 6-3, 6-4 win in 1 hour and 20 minutes just as she opened it — with a hold to love.

“The game I got broken before, I maybe took a little bit off on the first (serve). I was trying to go for a big kick, and it didn’t go my way,” Gauff said. “So knowing that it does take a lot to break me — I was just focused on trying to get out of it, and I knew if I could hold that game, I felt confident breaking the next game. And I did.”

It was a pretty straightforward first set for Gauff. She followed the love hold in the opening game with a break a few games later for 4-2. It turned out to be all she needed, as she served out the set from there. Coming in, Gauff had won 66 of her 70 completed Grand Slam matches where she had won the opening set and was undefeated in such matches at the US Open (14-0). Make it 67 of 71 and 15-0.

Gauff broke to begin the second and quickly consolidated for 2-0. But after Sonmez held in the following game, she responded with her first break for 2-2. It came at a point in the match when it seemed as if the Turk couldn’t miss, especially at the net, where she produced a string of volley winners. She finished 12 of 18 at the net compared to just 4 of 8 for Gauff.

But Gauff course-corrected with the critical hold for 3-all and followed it with a break in the next game to propel her to victory.

“I don’t know what put my mind at ease,” Gauff said in her post-match press conference. “I think maybe the confidence I had this week and knowing the opponent would have to play a really high level and me a really low level for it to not go my way. But Zeynep brought that high level today. I was just happy to get out of that second set.”

Gauff has now won seven of her eight US Open first-round matches and has 81 Grand Slam match wins since the start of 2020. Only Iga Swiatek (109) and Aryna Sabalenka (106) have more.

She’ll look to add to that tally in the second round, where she’ll face the winner of the suspended first-round match between Paula Badosa and Daria Kasatkina. Badosa led 6-1, 5-4 when rain stopped play.

Unfortunately for Gauff, she trails the WTA Tour Driven by Mercedes-Benz head-to-head against both players. Badosa holds a 5-3 advantage, winning their most recent meeting in Berlin earlier this year. Kasatkina leads 3-0, but they haven’t faced off since the 2022 WTA Finals.