From Wikipedia the free encyclopedia Naomi Osaka (大坂 なおみ, Ōsaka Naomi, Japanese pronunciation: [oːsaka naomi], born October 16, 1997) is a Japanese professional tennis player. She has been ranked No. 1 by the Women's Tennis Association (WTA) and is the first Asian player to hold the top ranking in singles. She is a four-time Grand Slam singles champion, and is the reigning champion at the US Open and the Australian Open. Her seven titles on the WTA Tour also include two at the Premier Mandatory level. At the 2018 US Open and the 2019 Australian Open, Osaka won her first two Grand Slam singles titles in back-to-back Grand Slam tournaments and is the first player to achieve this feat since Jennifer Capriati in 2001. She also became the first woman to win successive Grand Slam singles titles since Serena Williams in 2015.