"That is extraordinary," the commentator exclaimed.
The 31-year-old finished the match with 39 winners and 18 unforced errors. She secured a 2-6, 6-2, 6-1 victory in two hours and 13 minutes to book a spot in the quarter-finals, where she will face world No. 18 Elise Mertens.
"My fighting spirit brought me into the game," Azarenka said.
"I started to pick up my game from there. I think it was the jump-start — my fighting spirit.
"(Krejcikova) started playing really well … I felt like she played really well the whole match, but she just played so loose. I didn't necessarily feel I played bad, she was just one step ahead, and I felt like everything was kind of working. What helped me was kind of to understand that I had to change and adapt.
"I needed to adjust, find a new tactic, be more aggressive, come in a little bit more, and impose myself a bit more effectively."
