Jessica Pegula knocked out top seed and fellow American Coco Gauff 7-5, 7-6 (2) in a rain-interrupted semifinal clash and went on to beat Anna Kalinskaya 6-7 (0), 6-4, 7-6 (3) in the final to win the Berlin Open on Sunday.
The semifinal was suspended Saturday due to rain, with world No. 5 Pegula leading 7-5, 6-6 (3-1). She wasted no time after the match resumed under a cloudy sky Sunday, winning four of the last five points to reach the final.
"I played some really good tennis this week and I feel like I beat some really good girls, especially on grass," Pegula said after her first WTA title this year and fifth of her career. "To be able to gut out a win like that is cool."
Pegula lost a competitive first set to Kalinskaya after both players broke the other three times each. But the American bounced back, breaking in the first game to set up a win in the second set.
Pegula, 30, broke Kalinskaya to take a 3-1 lead in the third set, but the Russian player fought back with a break of her own and saved four break points in the next game to make it 4-4.
Kalinskaya, 25, was on the verge of two more breaks that would have taken her to victory, but the American saved five match points to win both games and take the set into the tiebreaker, where she ultimately prevailed.
The win marked Pegula's fifth career singles title and first on grass, days before she competes in Wimbledon, where she reached the quarterfinals last year.
Reuters and The Associated Press contributed to this report.