Coco Gauff had hoped to prove her mettle at the Cincinnati Open after a string of defeats by lower-ranked players, but the American will be seeking answers back at home after a stunning loss in her opener prematurely ended her title defence.

The Florida-based 20-year-old arrived in Cincinnati on the back of four tour-level losses to unfancied players going back to the French Open in June and was defeated 6-4, 2-6, 6-4 by Kazakh world No. 34 Yulia Putintseva on Thursday.

Putintseva, who beat top-ranked Iga Swiatek at Wimbledon, will face Spain’s Paula Badosa on Friday in the third round.

The defeat was a big blow to Gauff’s preparations for the August 26-September 8 US Open, where she will bid to retain her trophy.

“I feel like I have to work on consistency, overall,” Gauff, who will drop one spot to world No. 3 next week, told the WTA Tour after declining a press conference. “I’ll probably go home and try to reset,” she said.

“Obviously, I have a lot coming up soon with the U.S. Open, so I think just trying to reset and be ready for that.”

Gauff made 50 unforced errors in the match, including nine double faults, and said it was far from her best performance. “I made a lot of errors, especially when I was up 4-2 (in the third set). I think most of the points she won were off my errors,” Gauff said.

Gauff was not the only big name going out, as fourth seed Elena Rybakina crashed to a 3-6, 7-6(3), 6-4 defeat by former US Open runner-up Leylah Fernandez after squandering two match points.

In men’s action, No. 12 seed Ben Shelton outlasted Argentina’s Tomas Martin Etcheverry, 6-7 (6-8), 7-6 (9-7), 6-3. Brandon Nakashima, beat France’s Arthur Fils 7-5, 7-6 (7-3) to set up a meeting with No. 6 seed Andrey Rublev.

Fifth-seeded Hubert Hurkacz also reached the round of 16, but No. 8 Grigor Dimitrov and No. 9 Stefanos Tsitsipas were both ousted.