American Madison Keys defeated fellow rising star Jelena Ostapenko to move herself within one victory of reaching the world's top 10 at the Aegon Classic on Friday.
Keys, 21, beat 19-year-old Ostapenko 6-7 (1-7), 6-4, 6-2 to advance to the semi-finals in Birmingham.
While Keys had a solid clay court season by her standards, grass is where she really shines, and that was once again in evidence in her quarter-final match.
"I think I've been playing pretty well this week," Keys said. "I had a bit of a slow start in the first set, but I'm happy to be coming back tomorrow."
Ostapenko had beaten two-time Wimbledon champion Petra Kvitova in the previous round, and looked on course for another victory after taking the first set, but could not cope with Keys' impressive fightback in the last two sets.
"It's tough being on the tour for this long and being at the old age of 21; these 19 year olds are tough!" Keys quipped.
Should Keys reach the final, she will be assured of a place in the world's top 10.
But to do so she must first get past sixth seed Carla Suarez Navarro, who eliminated second seed Angelique Kerber courtesy of a hard-fought 6-4, 1-6, 7-5 victory.
The other semi-final sees unseeded duo Caroline Vandeweghe and Barbora Strycova square off.
Vandeweghe beat Yanina Wickmayer 6-4, 6-2, while Strycova was a 6-2, 7-5 winner over Tsvetana Pironkova.