STUTTGART, Germany - Anastasija Sevastova surprised Australian Samantha Stosur in the opening round of the Porsche Tennis Grand Prix, winning 6-1, 4-6, 6-3.
The Latvian, 27, overcame the former US Open champion, six years her senior, for the first time since 2010.
Sevastova lost in the first round of her only previous visit to the Porsche Arena in 2011, but made the last eight at the Volvo Car Open last month to begin her clay season, while Stosur is a former finalist in Stuttgart, losing to Justine Henin in 2010.
The Latvian was broken just once in the entirety of the one hour, 49-minute encounter, and although Stosur struck one more winner (22-21), she was undone by 34 unforced errors to Sevastova's 28.
Elsewhere on Tuesday, Barbora Strycova reached the secound round of this event for the first time in her career, beating lucky loser Jennifer Brady 6-2, 6-2.
The Czech is making her seventh appearance at the event, but just her third in the main draw. She will play Romanian fourth seed Simona Halep in round two.
Strycova was in command for the duration against her American opponent, who lost to Jelena Ostapenko in the final qualifying round on Monday before earning a reprieve following Dominika Cibulkova's withdrawal with a wrist injury,
Brady, who turned 22 earlier this month and reached a career-high ranking of World No.75 in the same week, was unable to do much damage on the Czech's serve, with the 31-year-old dropping just nine points in eight service games in the match.
In other early action, No.8 seed and former champion Svetlana Kuznetsova surived a game effort from Kiki Bertens in over two-and-a-half hours, 6-3, 5-7, 6-3, while qualifier Anett Kontaveit booked a second-round meeting with No.5 seed Garbiñe Muguruza by beating Ana Konjuh, 7-6(5), 6-4.
"I always have tough matches against Kiki," Kuznetsova said after the match. "I played three sets against her at the French Open a couple of years ago, and last year I lost to her in Fed Cup. I thought it was a great match. It's great that I have a day off tomorrow!"
The first set between the two saw four straight breaks to end it in Kuznetsova's favor, but the second set saw the first 10 games go with serve before Bertens earned the deciding break in a hard-fought 11th game.
"I didn't attack her serve enough, didn't return enough in the second set, but the rest, I think it's a great match," Kuznetsova said. "In the middle of the second set, I was saying, 'Ay, dios' to my doctors, to my legs...I was saying, 'I'm 31!' In the third, I was better. I thought it was great for the first match [on clay]."
One break decided the final set in Kuznetsova's favor, and though the World No.20 saved a match point and forced the Russian to serve it out, the No.8 seed did so with aplomb, holding at love to finish the match.