Sloane Stephens lost in the first round of the Dubai Championship on Monday, the latest setback for the rising American star who reached the Australian Open semifinals.
Stephens, a career-high 16th in the world rankings since knocking out Serena Williams in Melbourne, lost to Sorana Cirstea of Romania 5-7, 6-3, 6-2.
"It was a rough day, and I think she obviously played some good tennis," Stephens said. "Every match isn't going to go the way you want it, and obviously I got a little frustrated. Things happen, but, I mean, no need to dwell on it."
Eleventh-ranked Marion Bartoli also advanced, coming from a set down to beat Klara Zakopalova 3-6, 6-4, 6-1.
Last week, the 19-year-old Stephens lost to Zakopalova in the third round of the Qatar Open after wasting two match points. She smashed her racket afterward.
Monday's match was much the same. Stephens led 5-4 when the 30th-ranked Cirstea hit two double-faults, but the Romanian broke back. Stephens broke a second time and won the set.
More poor serving from Cirstea allowed Stephens to get the early break in the second, but then the Romanian settled down, breaking an increasingly frustrated Stephens twice to win the set. At one point, Stephens let out a scream after a missed shot and was warned by the chair umpire for racket abuse when she slammed her racket down after hitting a forehand wide to fall behind 5-3.
Cirstea broke Stephens three times in the third to go up 5-2 and finished the match off when the American hit a weak return and then a backhand volley long.
Cirstea, who lost to Caroline Wozniacki in the second round of the Qatar Open, said she was giving away too many points off her serve.
She had 10 double-faults in the first two sets but only two in the decider. She also won all three of her break points and saved seven of 11.
"I started the second quite positive and I knew I had to be just a little more careful at the key points if I would turn it around," Cirstea said.
After beating an injured Williams at the Australian Open, Stephens was being billed as the future of American tennis, even though she hasn't won a professional tournament.
"The first week at home was really tough. Everyone was like, 'Oh, my God, I want to see you,'" Stephens said last week in Doha. "Of course I had people tweeting me and stuff. And I wanted to make time for my friends and see like the people who I was supposed to see."
Some of her recent woes can be blamed on health problems.
She pulled out of the Fed Cup against Italy this month after aggravating an abdominal muscle injury and getting a stomach virus.
Still, Stephens said little has changed from Australia and she hasn't let all the hype get the best of her.
"Obviously it's really tough week in and week out playing perfect tennis and just really being able to execute," Stephens said. "Some days you're going to be on the court and it's not just going to turn out the way you want. Like today, I didn't play my best tennis, and last week I didn't play my best tennis, but you just kind of got to move on."
AP Sports Writer Melissa Murphy in New York contributed to this report.