The Australian starts in January. Naomi Osaka is already hammering away in preparation for the Happy Slam. New mom Osaka shared some video of her recent hard-court practice sessions. View this post on Instagram A post shared by 大坂なおみ🇭🇹🇯🇵 (@naomiosaka) The four-time Grand Slam champion has reunited with former coach Wim Fissette and is gearing […]