DUBAI: Top seeds Serena Williams and Angelique Kerber have withdrawn from the WTA Dubai Open, organisers announced on Saturday. “We regret to announce that Serena Williams and Angelique Kerber have withdrawn due to illness and injury,” the Dubai Duty Free Tennis Championships wrote on their official Twitter account ahead of the draw. The news is a double blow for organisers with Williams and Kerber seeded No 1 and 2 respectively. The 28-year-old German shocked Williams in the Australian Open final to win her first Grand Slam title. Williams said she was suffering from flu, while Kerber blamed a right upper thigh injury. The withdrawals follow that of Agnieszka Radwanska and Alize Cornet. Defending champion Simona Halep is now the top seed in the tournament which starts on Monday with world number five Garbine Muguruza of Spain moving up to second seed.