MARTA KOSTYUK was such a perfectionist when she started playing tennis as a child, she'd blow up in anger if she missed even a single ball. It made tennis completely unenjoyable.

"I always want to win, no matter what," the Ukrainian teenager said. "If I was losing, it was a tragedy. It was, like, I don't want to play anymore."

Now, after beating Olivia Rogowska 6-3 7-5 today to become the youngest player to reach the Australian Open third round in two decades, Kostyuk is finding peace with the ups and downs of the sport. All at the wise old age of 15.

"Now, I start to enjoy it," she said. "Finally."

Kostyuk's performance in Melbourne is remarkable considering just how far she's come in such a short time. The Australian Open is not only her first grand slam, but her first main draw at any WTA-level tournament.

Her ranking? No 521. Career earnings? Less than £5,000.

Yet the bubbly Kostyuk's game looks more than ready for this moment. Granted a wildcard to the qualifying draw after capturing the Australian Open junior title last year, Kostyuk won three matches to earn a spot in the main draw, then upset the No 25-seeded Chinese veteran Peng Shuai in the first round.

Perhaps an even tougher challenge, she followed that up with a convincing win over Australian wildcard entry Rogowska in front of a partisan crowd at Margaret Court Arena, the No 2 show court at Melbourne Park.

The stats weren't pretty — 45 unforced errors to just 22 winners — but Kostyuk handled the pressure well. A power player who hits big off both sides, she kept going for her shots even when she misfired.

And misfire she did aplenty. While serving for the match, she clubbed a ball off the frame of her racquet that nearly hit a spectator in the crowd. (Kostyuk blamed serving into the sun: "You throw the ball and you hit the sun, actually.")

Kostyuk was an acrobat growing up and was so talented she placed fourth in the Ukrainian national championships — as a child. But she wanted to spend more time with her mother, a former pro tennis player and now coach, so she gave up acrobatics to focus on tennis at age 11.

Since winning the Australian Open girls title last year, she's made the jump to the pro level and is represented by a high-profile manager, former world No 3 Ivan Ljubicic, who currently coaches Roger Federer. The impact on her game has been immediate.

"Ivan is always helping me when he sees me," she said. "And Roger, we speak twice. You know, really, like speak. Not like: 'Hey, how are you.' That was nice."

With her run in Melbourne, Kostyuk has now become the youngest player to reach the third round since Martina Hingis made the quarter-finals at age 15 in 1996.