Jessica Pegula advanced to her second straight Australian Open quarterfinals with a 7-6 (0), 6-3 upset victory over No. 5 seed Maria Sakkari.
The 21st-seeded American hit 15 winners as she dispatched Sakkari in one hour and 35 minutes.
Pegula will take on top-seeded Ash Barty or Amanda Anisimova in the next round. She holds an 0-1 record against Barty and defeated Anisimova in their only previous meeting.
Sakkari made two Grand Slam semifinals last year but has never advanced past the fourth round at the Australian Open.