But a collective gasp rang out across Court 3 when the teenager revealed in a post-match, on-court interview that she was born in 2002 and is only 15 years of age, reports Xinhua news agency.
The feat makes Kostyuk the youngest player to reach the third round at the Australian Open since Martina Hingis in 1996.
After gaining a straight sets victory over China's Peng Shuai in her first round match, the 6-3, 7-5 win over Rogowska will now see her face fellow Ukrainian and fourth seed in the tournament, Elina Svitolina.
To date, the teenage sensation has only pocketed a little over $6,000 in prize money during her short career. However, her passage into the third round will now guarantee Kostyuk in excess of $100,000.
"I already know where I'm going to spend this," she told reporters after the match.
"First of all I will get presents for my family, because I have big family.
"And then for myself a bit," she added.
When asked about the next round match with her compatriot Svitolina, Kostyuk said that she "will just enjoy it".
"I think I'm going to play on the big court again, so I will just try to show my best tennis," she predicted.
Another young talent, Belinda Bencic of Switzerland, was riding high after knocking out last year's Australian Open finalist, Venus Williams, in straight sets. But on Wednesday, the 20-year-old came crashing back down to earth, exiting the tournament in the second round at the hands of World No.124, Luksika Kumkhum, who won 6-1, 6-3.
The 24-year-old Thai was superb, showing fierce power at the baseline and having tremendous success attacking the net.
"It's the first time that I've reached the third round," Kumkhum said. "I kept telling my coach and family I'm trying so hard to pass the second round, so I'm so happy."
With many expecting the second round match up to be a walk in the park in comparison to Venus Williams, Bencic quickly talked down any speculation that she underestimated her opponent.
"I've played her a few times and it's always been really difficult," Bencic explained. "I had re-set and focused but it was a tough second round."
"It was not the issue that I was still thinking about the Venus win," she added.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
