By Rozanna Latiff
MELBOURNE (Reuters) - With composure that belied her age, Coco Gauff claimed the biggest win of her young career on Friday with a stunning upset of defending champion Naomi Osaka at the Australian Open to reach the fourth round.
The 15-year-old American took advantage of a misfiring Osaka for a brutally efficient 6-3 6-4 win in just 67 minutes on Rod Laver Arena.
Gauff, who had beaten seven-times Grand Slam champion Venus Williams in her Australian Open debut on Monday, said the win over Osaka ranked "somewhere around the top" of her biggest scalps.
"I thought I played really well today and I was pretty composed and really calm," she told reporters.
After losing to Osaka 6-3 6-0 at the U.S. Open last year, Gauff said she felt less pressure and more confidence this time around against the Japanese third seed, whose aggressive and heavy groundstrokes had troubled her in their previous meeting.
"She definitely plays faster than most players. I think at the U.S. Open, I wasn't really prepared for that."
"I feel like now I'm more playing, just having fun. And I mean, winning is a cherry on top but I'm honestly having a lot of fun on the court, even in those tight situations," said Gauff.
Gauff, who said she took a break from homework to play her night matches, dazzled the crowd with her poise, holding serve efficiently before a string of backhand errors off Osaka's racket gave the teenager the break midway through the first set.
Osaka appeared to stem the tide after fighting back from a break down early in the second set, but could not keep up the momentum against the steady Gauff.
Gauff won a second break to go up 4-3 amid another flurry of errors from Osaka, before serving out the victory with aplomb.
She next plays either China's Zhang Shuai or American 14th seed Sofia Kenin for a place in the quarter-finals.
Osaka was the third former women's champion to bow out at Melbourne Park on Friday after her immediate predecessors Caroline Wozniacki and Serena Williams lost their respective matches earlier in the day. German Angelique Kerber, who won in 2016, remains in the draw.
(Reporting by Rozanna Latiff; Editing by Toby Davis)
