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.

Real Madrid handed shock home loss as Celta Vigo spring surprise
Dubai Capitals overpower Abu Dhabi Knight Riders by 83 runs
Mid East finished strong with victory against Arabia
Norris takes F1 title as Verstappen wins Abu Dhabi race
Neser fires Australia to eight-wicket win in second Ashes test
