The world number one lost on Tuesday night in straight sets to Dubai resident Kristina Mladenovic.
Meanwhile, fourth seed Karolína Plíšková is through to the next round after beating Dominika Cibulková in three sets.
Petra Kvitová, the 2013 Dubai Duty Free Tennis Championships winner, is in action later Wednesday.
The second seed takes on the USA's Jennifer Brady on Centre Court at 11:00 am.
Simona Halep, Angelique Kerber and two-time defending champion Elina Svitolina also play their round of 16 matches later today.

Wood claims MENA Golf Tour rankings title after regional tensions end season
Klopp shuts down Real Madrid speculation, still open to coaching return
AFC confirm Jeddah to host postponed Asian Champions League matches
Madrid's Mbappe fit and ready to play every game before World Cup
Cerundolo's Miami magic continues with stunning Medvedev upset
