Ana Ivanovic defeated Francesca Schiavone 6-1, 7-5 Tuesday to advance to the second round of the Dubai Tennis Championships.
Peng Shuai of China ousted six-seeded Marion Bartoli 6-4, 6-3, winning six straight games to wrap up the final set.
Ivanovic breezed through the first set, holding her Italian opponent to just one game in 33 minutes. Schiavone made it competitive in the second set, but was no match for the 24-year-old Serb.
Also, fifth-seeded Agnieszka Radwanska of Poland advanced after defeating Aleksandra Wozniak of Canada 6-1, 6-7 (6), 7-5.
Radwanska cruised through the first set in 27 minutes, but she needed another 2 hours to win her opening match. After losing the second set on a tiebreaker, Radwanska struggled with her concentration in the third. She rallied from 5-3 down to win 7-5.
On Tuesday, two more players joined the list of withdrawals.
Dominika Cibulkova of Slovakia retired with a hamstring injury while trailing Iveta Benesova 3-1, and Maria Kirilenko withdrew from a doubles match with Sabine Lisicki against Anabel Medina Garrigues and Alicja Rosolska.
Kirilenko has a neck injury but is scheduled to play Ivanovic in the second round on Wednesday, organizers said.
Peng will play Slovakia's Daniela Hantuchova in the second round. Hantuchova advanced after defeating Polona Hercog of Slovenia 1-6, 7-5, 7-6 (4).
Third-seeded Caroline Wozniacki will open the defense of her title on Wednesday when she meets Simona Halep of Romania. Halep advanced Tuesday after defeating Russia's Anastasia Pavlyuchenkova 6-4, 6-2.
Also, Lucie Safarova defeated Petra Martic 6-3, 5-7, 6-3. Safarova will meet U.S. Open champion Samantha Stosur in the second round.
Australian Open champion Victoria Azarenka is the top-seeded player in Dubai. The top-ranked Belarusian will meet Julia Goerges of Germany in her opening match on Wednesday.
Wimbledon champion Petra Kvitova, French Open winner Li Na and Vera Zvonareva withdrew because of illness or injury on Monday.