Key Biscayne - Former champion Agnieszka Radwanska has won her opening match at the Miami Open on Thursday, beating Anna Schmiedlova 6-4, 7-5.
Radwanska, the 2012 champion, has advanced to at least the quarterfinals each of the past five years. She's seeded seventh, and all seeded players had first-round byes.
No. 9 Andrea Petkovic beat American Christina McHale 6-2, 6-2.
No. 2 Maria Sharapova and No. 16 Venus Williams were scheduled to play their opening matches later Thursday.
On the men's side, American Steve Johnson lost to Mikhail Kukushkin 6-4, 3-6, 6-2. Marcos Baghdatis lost to Simone Bolelli 6-2, 6-2.
Martin Klizan won and will face No. 1 Novak Djokovic in the second round Saturday night.