Petra Kvitova powered past Wimbledon champion Garbine Muguruza in Sunday's US Open night session to reach the quarter-finals.
The Czech 13th seed fought back from 1-4 down in the first set to win 7-6 (7-3) 6-3.
It is Kvitova's best effort at a Grand Slam since she reached the last eight in New York two years ago.
The 27-year-old returned to action in May following a knife attack at her home last December.
She required extensive surgery on her left hand and confirmed only last week that it still did not feel completely back to normal.