Coco Gauff beat Marta Kostyuk 7-6 (6), 6-7 (3), 6-2 in an error-strewn match at the Australian Open on Tuesday to claim a place in the semifinals.
The fourth-ranked Gauff saved two set points as she came from 5-1 down to take the opening set on the tiebreaker but was pushed to a deciding set before clinching victory after 3 hours, eight minutes.
Gauff hit 51 unforced errors, nine double faults and just 17 winners but survived to set up a meeting with defending champion Aryna Sabalenka or No. 9 Barbora Krejcikova in the semis.
The American has now won 12 straight matches in Grand Slam tournaments after winning the U.S. Open last September.
No. 1 Novak Djokovic is in action later, taking on Taylor Fritz for a place in the semifinals.