Coco Gauff earned her second semi-final at the WTA 1000 level on Thursday with a 6-2, 7-5 defeat of practice partner Madison Keys in Dubai.
The teenaged winner also achieved the final four in the elite series in Rome two years ago.
Gauff took full advantage of an opponent whose game she knows well, with former US Open finalist Keys not helping her own cause with 22 unforced errors and just one winner in a first set lasting for less than half an hour.
Gauff moved into a Friday semi against dominant top seed Iga Swiatek, who moved to the final four with a walkover as quarter-final opponent Karolina Pliskova had to pull out with illness.
“I had to stay in the moment, she’s not easy to play,” the winner said. “I knew it would be a tough match from the start.
“It’s not easy to beat someone whose game you know so well — but they also know what you are going to do.
“We trained together last week (in Doha). I just had to stick to my game plan.”
Gauff, who broke Keys to love in the penultimate game, served out the victory moments later after 81 minutes.
She now takes a 0-5 record into her match with Swiatek.
“She’s playing great tennis, I will have no pressure,” the American said.
“I’ll try to play my game, but I’ve gotten better since we last played (three months ago in Fort Worth).
“A ranking is just a number – you have to come out on court believing that you can win.”