Coco Gauff moved into the Top Seed Open quarter-finals with an impressive win in Lexington on Wednesday.
The 16-year-old edged past second seed Aryna Sabalenka 7-6 (7-4) 4-6 6-4 at the WTA International event.
Gauff, who reached the fourth round at the Australian Open this year, twice gave up a break lead in the final set before making the most of her third chance.
The American moved into the last eight, where she will face eighth seed Ons Jabeur.
Jabeur also battled, beating qualifier Olga Govortsova 3-6 6-2 6-4.
Jennifer Brady and Marie Bouzkova claimed straight-sets wins to reach the last eight.
Brady crushed sixth seed Magda Linette 6-2 6-3, while Bouzkova was too good for Anna Blinkova 6-4 6-2.