Teenager Jelena Ostapenko beat Petra Kvitova for the second time this season at the Aegon Classic Birmingham on Thursday.
The 19-year-old Latvian is a former junior champion at Wimbledon and once again showed she is a formidable player on grass by beating Kvitova, a two-time Wimbledon champion, 6-4, 4-6, 6-3.
"Since juniors, I think I did well on grass. It's my first time here, but I really like it here," Ostapenko said. "I think grass is my favorite surface, so I'm looking forward to two more tournaments. I think I can do well on grass because I have good serve and good backhand and forehand, so for grass, I think it's good.
"I mean, she's one of the most dangerous opponents (on grass) because she won twice Wimbledon. I'm happy to win today."
Ostapenko defended three break points in the seventh game before going on to snatch a lone break point in the next game, taking a decisive lead in the first set.
Kvitova fought back strongly to win a second set interrupted by rain, but Ostapenko finished the stronger of the two in the decider, wiping out an early deficit before going on to gain the upper hand.
She moves on to face American Madison Keys, who brushed aside qualifier Tamira Paszek, 6-1, 6-3.
Others to advance on the day included Johanna Konta, Tsvetana Pironkova and Yanina Wickmayer, who resumed her match with Caroline Wozniacki that had started the day before and completed a 6-4, 6-7 (5-7), 6-2 victory.
Several more matches were due to be completed on the day but the rain would return and force another suspension.