No.5 seed Coco Gauff of the United States capped off a breakthrough day by booking a spot in the Round of 16 at the Guadalajara Open Akron with a 7-6(1), 6-3 win over Italian qualifier Elisabetta Cocciaretto.

The victory bolstered an already splendid Wednesday for Gauff, who had earlier qualified for the singles field at the WTA Finals in Fort Worth. Aryna Sabalenka’s loss to Liudmila Samsonova guaranteed both Gauff and Caroline Garcia places in the eight-woman field.

Gauff will be at the WTA Finals in singles and doubles after a stellar season in both disciplines. Last week, Gauff and Jessica Pegula became the fifth pairing to qualify for the doubles field.

'Buy one, get one free!': Gauff reacts to qualifying for WTA Finals

Even though her spot was already sealed, Gauff still battled for a challenging triumph over World No.92 Cocciaretto. Gauff would have qualified for the WTA Finals in singles with a win over Cocciaretto, regardless of any other results. 

Cocciaretto had garnered her first WTA 1000 main-draw victory by ousting Anastasia Potapova in this week's opening round. Gauff, though, ended the qualifier's run in 1 hour and 47 minutes.

Gauff and Cocciaretto had never previously faced off in the pros, but they met twice during their junior days, splitting their two meetings in 2018. In their first tour-level meeting, Gauff slammed seven aces and broke Cocciaretto four times.

Cocciaretto started strongly, breaking Gauff in the opening game, but a backhand winner plumb on the sideline allowed Gauff to break back for 3-3. The qualifier did not go down meekly, using deft angles to stay with Gauff all set, even saving three consecutive set points at 6-5.

But Gauff began the crucial tiebreak with a backhand crosscourt winner, and she steamrolled to a commanding 6-1 lead and her fourth set point. There, Gauff fired an unreturnable serve to win her sixth tiebreak at WTA 1000 events this season, more than any other player on tour.

Gauff romped to a 5-1 lead in the second set, and though she was unable to serve out the match at 5-2, the American gritted through a tough game to break for the win.

Gauff will face another Italian in the Round of 16 when she meets World No.28 Martina Trevisan. They have previously met twice, both times at Roland Garros -- Trevisan won in the 2020 second round, but Gauff avenged that loss in this year's semifinals. 

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Joining Gauff in the Round of 16 is No.8 seed Veronika Kudermetova, who defeated surging Donna Vekic 6-4, 7-5 in 1 hour and 38 minutes.

Vekic had won nine of her last 11 matches, with a run to last week's San Diego final as a qualifier behind her. However, Kudermetova continued her consistent season by stopping Vekic with 11 aces and a stunning 93 percent success rate behind her first serve.

Kudermetova is still one of the main contenders to grab one of the last three singles spots at the WTA Finals. In the Round of 16, she will face No.12 seed Jelena Ostapenko, who also has an outside chance to qualify for the WTA Finals if she can win the title and hope other results break her way.

Ostapenko won their only previous meeting, in this year's Dubai final, by a commanding 6-0, 6-4 scoreline.