Miami, FL, USA: World No.1 Victoria Azarenka earned a hard-fought victory over Michaella Krajicek 6-3, 7-5 in the Sony Ericsson Open to extend her season’s winning streak to 24-0 on Friday afternoon.

Azarenka, a two-time champion at the Sony Ericsson Open and this year's top seed, looked headed for a routine straight set win as she built a 6-3 4-2 lead, but Krajicek won three games in a row to give her an opportunity to serve for the second set at 5-4. But Dutchwoman double faulted three times and eventually got broken and Azarenka closed it out at 7-5.

Azarenka will now play British wildcard Heather Watson who upset No.27 seed Lucie Safarova in the second round.

Meanwhile, No.5 seed Agnieszka Radwanska, No.20 seed Daniela Hantuchova and No.22 seed Maria Kirilenko all came through with wins too, but No.11 seed Francesca Schiavone wasn't so lucky, squandering a 3-0 third set lead and falling to Ksenia Pervak, 6-4 4-6 7-5. Pervak's win over the World No.12.