Defending champion Victoria Azarenka was back in action on Key Biscayne. The noisiest No. 1 since Maria Sharapova, Azarenka won her opening match over Michaella Krajicek, 6-3, 7-5.
It was Azarenka’s 24th victory in a row. The streak began with her first match this year, and her start is the best since Martina Hingis went 37-0 in early 1997.
“I’m not really thinking about numbers, the streaks, whatever,” Azarenka said. “It’s your job to count; mine is to play tennis.”
On the men’s side, No. 10 seed and former Georgia Bulldog John Isner overcame a slow start to beat Nikolay Davydenko 2-6, 6-3, 6-4. Davydenko retreated eight feet behind the baseline to better cope with the 6-foot-9 Isner’s booming serves, but failed to break in the final two sets.
Also reaching the third round was No. 4 Andy Murray, who beat Alejandro Falla 6-2, 6-3.
Murray, the 2009 champion, bounced back from a loss in his first match at Indian Wells two weeks ago. He also avoided a repeat of last year, when he lost his opening match at both Indian Wells and Key Biscayne.
With the victory, Murray improved to 15-3 this year.
Other seeded men to advance included No. 6 Jo-Wilfried Tsonga, No. 9 Janko Tipsarevic, No. 13 Gilles Simon, No. 18 Alexandr Dolgopolov and No. 22 Jurgen Melzer.
No. 15 Ana Ivanovic lost only six points on her first serve and beat Vania King 6-4, 7-5. Ivanovic was playing for the first time since she retired with a left hip injury a week ago at the Indian Wells semifinals.
Two wild cards eliminated seeded women. Garbine Muguruza Blanco upset No. 9 Vera Zvonareva 6-4, 6-3, and Aleksandra Wozniak rallied past No. 28 Monica Niculescu 4-6, 6-3, 6-4.