DUBAI, Feb 20: Grand slam winners Petra Kvitova and Samantha Stosur strolled into the second round of the Dubai Open along with former world number one Caroline Wozniacki with straight sets wins on Tuesday.

Kvitova, the former Wimbledon champion from the Czech Republic, showed evidence of an encouraging surge in form and fitness as she thumped Slovakian Daniela Hantuchova 6-2, 6-1 to set up a second-round match with former No 1 Ana Ivanovic.

Former US Open Champion and seventh seed Stosur, of Australia, brushed aside 19th-ranked Ekaterina Makarova 6-3, 6-1 while eighth seed Wozniacki was similarly dominant in beating Lucie Safarova 6-2, 6-2.

Meanwhile, Serena Williams pulled out of the Dubai Open, partly to consolidate her remarkable return to world number one two days ago by focusing on her home tournament, in Miami, in the second half of next month.

“I am just not well — it’s my back,” Serena explained. “All athletes really get this.

“I really can’t move. It would be a horrible performance for you guys. It’s just really sad for all of us. I hope to continue here, but unfortunately it won’t be this year.”

Williams took over the No 1 ranking last week in Qatar, the sixth time in her career she has been the top-ranked player in the world. Last year, she won the Wimbledon and US Open titles, as well as the Olympic gold medal.

Results (prefix number denotes seeding): First round: 7-Samantha Stosur (Australia) bt Ekaterina Makarova (Russia) 6-3, 6-1; Roberta Vinci (Italy) bt Svetlana Kuznetsova (Russia) 6-3, 6-2; 8-Caroline Wozniacki (Denmark) bt Lucie Safarova (Czech Republic) 6-2, 6-2; Zheng Jie (China) bt Urszula Radwanska (Poland) 6-2, 2-6, 7-5; 6-Petra Kvitova (Czech Republic) bt Daniela Hantuchova (Slovakia) 6-2, 6-1; Nadia Petrova (Russia) bt Dominika Cibulkova (Slovakia) 5-7, 6-3, 6-2; 5-Sara Errani (Italy) bt Julia Goerges (Germany) 6-3, 4-6, 6-4.—Agencies