<p>DUBAI, United Arab Emirates — American teen Coco Gauff led a day of upsets in the second round of the Dubai Championships on Tuesday, when top-seeded Elina Svitolina lost and Petra Kvitova dropped out with a hip problem.</p>
<p>The 16-year-old Gauff fought back to defeat 12th-seeded Marketa Vondrousova 3-6, 6-0, 6-4 to set up a third-round clash with Tereza Martincova, who upset the fifth-seeded Kiki Bertens 6-1, 6-4.</p>
<p>Svetlana Kuznetsova upset two-time champion Svitolina 2-6, 6-4, 6-1, completing her comeback win in just under two hours and will face Barbora Krejcikova in the third round. The Czech defeated Jelena Ostapenko 6-3, 6-1.</p>
<p>Another teenager, 19-year-old Anastasia Potapova, defeated 11th-seeded Madison Keys 6-4, 6-3.</p>
<p>Kvitova, who defeated Garbiñe Muguruza to win the Qatar Open on Saturday, retired Tuesday with Jil Teichmann leading 6-2, 3-4. Kvitova said she’s had an adductor problem since the semifinal in Doha.</p>
<p>French Open champion Iga Swiatek eased past lucky loser Misaki Doi, 6-2, 6-4 for a third-round clash with Muguruza, who defeated American teenager Amanda Anisimova, 6-4, 6-2.</p>
<p>The second-seeded Karolina Pliskova had to dig hard for a 6-3, 6-7 (5), 6-2 win over Anastasija Sevastova and the sixth-seeded Belinda Bencic also had a tough match in beating Veronika Kudermetova 6-4, 5-7, 6-4. Bencic needed five match points to seal her win.</p>
<p>Elise Mertens defeated Shelby Rogers 6-3, 6-3, but another American, Jessica Pegula, prevailed with a 6-1, 6-2 win over Kristina Mladenovic.</p>
<p>There were wins, too, for Caroline Garcia, Anett Kontaveit, Aryna Sabalenka, and Ons Jabeur.</p>
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