"Two weeks ago I played an ITF 25K and I lost in the first round," Kostyuk said after defeating Peng. "I lost the first round to a Greek girl. I was up and I had set point and I made some mistakes in that moment.
"After the match, I was so upset. 'I don't want to go to Australia, I don't know what I'm going to do here, why am I coming here, I'm going to lose first round of qualies.' It was like this. Mum was like calm down, it's fine. That's why we came one tournament before. You learn from your mistakes and it will be better."
"I learned from my mistakes and I actually changed a lot here. So in one week I managed to change so many things, you cannot imagine."
The youngster took full advantage of facing wildcard entrant Rogowska in the second as she looks to improve her world ranking of 522.
