Kurumi Nara of Japan claimed her maiden WTA title by upsetting Klara Zakopalova 6-1 4-6 6-1 in the final of the Rio Open.
The 22-year-old - normally more at home on hard courts - mastered the top seed on the Brazilian clay, coming out on top at the end of a see-saw match that she looked like would be over in straight sets.
On three occasions she broke Zakopalova's serve in the second, only to quickly surrender the advantage, allowing the Czech to force a decider.
However Nara regained her composure to breeze through the third set, converting four of her seven break-point opportunities and secure victory after two hours and four minutes on court.
"I love Rio," Nara - who becomes the ninth Japanese player to win on the WTA Tour - said afterwards. "I can't believe I won the tournament, but I am very happy."
The victory is likely to push Nara into the top 50 when the WTA publishes its revised rankings on Monday
Zakopalova, meanwhile, has now lost 12 consecutive singles finals. In parts of the match she seemed unwell, seemingly struggling to cope with the high heat and intense humidity.
"I have an asthma problem so I couldn't breathe," she said. "But it's not an excuse. Well done to Kurumi. She deserved it. She played really well."