The defending Cincinnati Open women's singles champion, Coco Gauff of the U.S., lost to Yulia Putintseva of Kazakhstan 4-6, 6-2, 4-6 in the second-round match on Thursday.

"It was not the best match for me," Gauff said in an interview with the WTA Tour. "I made a lot of errors, especially when I was up 4-2 (in the third). I think most of the points she won were off my errors. She's always a tricky opponent to play. She mixes up the ball. She has drop shots, slice. She's kind of someone that makes you earn the match."

This was Putintseva's first win over Gauff after suffering three straight losses to the current world No. 2. Back in July, she upset world No. 1, Iga Swiatek of Poland, at the Wimbledon Championships. Putintseva's next opponent at the Cincinnati Open will be Paula Badosa of Spain in the Round of 16.

"Belief is never an issue for me. Since I was a kid, I remember that only my parents believed in me," Putintseva told Tennis Channel after Thursday's victory. "They were the only ones who thought I would be able to do well due to my height. I was the smallest person in the group, and my father was like, 'You're the best. You have to believe that you're the best, otherwise it's not going to work.'"

Aryna Sabalenka of Belarus, the No. 3 seed of the tournament, beat Elisabetta Cocciaretto of Italy 6-3, 6-4 to begin her tour at the Cincinnati Open this year. It's the sixth win out of her seven open matches at Cincinnati.

"I'm happy with my level in the tough moments," Sabalenka said. "Elisabetta is a difficult opponent. She fought to the last point." She will face Elina Svitolina of Ukraine next.