Tennis: 15 year old Marta Kostyuk stuns Australian Open

15-year-old Marta Kostyuk of Ukraine celebrates her victory. Photo / Getty

Not since Martina Hingis has a young female star gone this far at such a young age.

Ukrainian 15-year-old Marta Kostyuk became the youngest player to make it into the third round at the Australian Open since the former Swiss world No. 1 by defeating Australia's Olivia Rogowska 6-3 7-5 on Wednesday.

"Are you joking?" a Channel 7 commentator said. "This is an incredible story."

Kostyuk earned a place in qualifying after winning the junior title last year, before becoming the youngest grand slam entrant since 2005.

She upset Chinese 25th seed Peng Shuai 6-2 6-2 in the opening round to become the youngest non-wildcard to a win slam match since 1997.

"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.

Marta Kostyuk closes it out with some humor. Shanks a serve on 1st MP & motions to challenge it. Eventually converts to win 63 75.

- Youngest in 3R at a Slam since 1997 (Lucic-Baroni, USO)
- Youngest in 3R at #AusOpen since 1996 (Hingis)
Get to know her: https://t.co/hkND0FXK84

— WTA Insider (@WTA_insider) January 17, 2018