Victoria Azarenka and Agnieszka Radwanska cruised into the Qatar Open third round with straightforward wins on Wednesday, while Samantha Stosur also won.
Stosur registered her first win since the Australian Open with a 6-4 1-6 6-3 victory over Romania's Monica Niculescu.
The eighth seed, who gave up a 5-2 lead in the third set in her loss to China's Zheng Jie in the second round at Melbourne Park, took just under two hours to advance.
Stosur will now meet Russian Svetlana Kuznetsova, who beat French ninth seed Marion Bartoli 6-4 6-4.
In her first match since winning the Australian Open in January, Belarusian world number one Azarenka eased past Switzerland's Romina Oprandi 6-2 6-3 in Doha.
Azarenka, champion at the WTA Premier tournament last year, made a slow start but recovered to win in 72 minutes.
The two-time grand slam champion was two points away from conceding a 3-0 lead in the first set before a more patient approach paid off.
Azarenka will face Christina McHale in the next round after the American was a surprise 6-4 6-2 winner against Czech 17th seed Lucie Safarova.
Radwanska was as convincing as Azarenka, disposing of Australian qualifier Anastasia Rodionova 6-3 6-2.
Awaiting the Polish fourth seed in the next round is Serbian 13th seed Ana Ivanovic, who took the first set against Simona Halep 6-3 before the Romanian retired.
Other winners on Wednesday included Danish 10th seed Caroline Wozniacki, who battled early before brushing past Romanian Sorana Cirstea 7-6 (9-7) 6-0.
Australian Open semi-finalist Sloane Stephens, the American 16th seed, suffered a 4-6 7-6 (7-5) 7-6 (7-5) loss to Czech Klara Zakopalova, whose countrywoman Petra Kvitova took the first set 6-4 over Ekaterina Makarova before the Russian retired.
Russian 11th seed Nadia Petrova edged Chinese Taipei's Hsieh Su-Wei 3-6 6-2 6-4, Pole Urszula Radwanska overcame Italian 15th seed Roberta Vinci 6-2 5-7 6-0, Slovakian Daniela Hantuchova was too good for Russian Ekaterina Bychkova in a 6-3 1-6 6-3 win and Italian sixth seed Sara Errani breezed past Hungarian Timea Babos 6-4 6-0.
