Serena Williams, Angelique Kerber withdraw in Dubai

Top seeds Serena Williams and Angelique Kerber have withdrawn from next week's Dubai Tennis Championships.

Organisers were dealt a double blow after world number one Williams pulled out with illness, while world number two Kerber is nursing a thigh injury.

Last month, Kerber shocked Williams in the Australian Open final to win her first grand-slam title.

Agnieszka Radwanska and Alize Cornet had already pulled out of the tournament.

Defending champion Simona Halep takes the number one seeding in the absence of Williams, while Garbine Muguruza will be seeded second.