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.