Japan's Naomi Osaka followed her first career title by knocking former world No. 1 Serena Williams out of the Miami Open in straight sets Wednesday.Fresh from winning Sunday's BNP Paribas Open final, the 20-year-old Osaka did not concede a break point on her way to beating childhood idol Williams 6-3, 6-2 in the opening round.On the comeback trail following the birth of her first child, Williams looked some way off regaining the form that earned her 72 WTA singles titles, including eight in Miami.She hit 28 unforced errors to just 16 winners as she exited the tournament before the fourth ro…READ FULL ARTICLE