The American is no longer with Top 5 Management.
Back injury knocks 2008 AO finalist out of Melbourne.
The 20-year-old currently sits at No.21 in the ATP rankings.
Roger Federer and Rafael Nadal return, and Gilles Simon is added.
Rafa Nadal was recently appointed as honorary ambassador of the Food Bank of Mallorca.
Play Academy with Naomi Osaka is an initiative to keep girls in sport.
A 16-year-old Rafa Nadal's tennis dream was both beautiful and powerful.
