https://sports.yahoo.com/defending-c...093600758.htmlMELBOURNE (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.