Defending champion Kim Clijsters has won her opening match at the Sony Ericsson Open, routing qualifier Anastasiya Yakimova 6-1, 6-1.

Clijsters is seeded second and playing for the first time since retiring two weeks ago in the fourth round at Indian Wells with a right shoulder injury.

Yakimova committed 17 unforced errors yesterday and had only one winner in the 50-minute match.

The last American in the women’s draw was eliminated in the second round when Varvara Lepchenko lost to Petra Kvitova 6-1, 6-2.

Top-ranked Caroline Wozniacki alsowon her opening match by beating Bethanie Mattek-Sands 6-2, 7-5.

Wozniacki, coming off her 14th career title last week at Indian Wells, erased eight of the 10 break points she faced. She hit only five winners but committed just 15 unforced errors to 49 for Mattek-Sands.

“Bethanie is a tough player to play,” Wozniacki said. “You never know what to expect from her, and she’s going for her shots no matter where she’s standing on the court, and it’s difficult to get the rhythm.”

Seeded players were in action for the first time after having byes in the opening round. No. 16 Maria Sharapova, a two-time runner-up playing in the tournament for the first time since 2007, beat wild card Petra Martic 6-3, 6-2.

Among those eliminated were No. 7 Li Na, No. 10 Shahar Peer, No. 13 Flavia Pennetta and No. 18 Nadia Petrova.

Li lost to Johanna Larsson of Sweden 7-5, 6-7 (5), 7-6 (5). Peer was beaten by Anabel Medina Garrigues of Spain 6-2, 6-2. Pennetta lost to Iveta Benesova of the Czech Republic 6-3, 6-0. Petrova retired because of dizziness while trailing German wild card Sabine Lisicki 4-6, 6-3, 3-1.

No. 4 Sam Stosur beat Zheng Jie of China 6-2, 6-1, and No. 6 Jelena Jankovic eliminated Monica Niculescu of Romania 6-3, 6-1. No. 11 Svetlana Kuznetsova, the 2006 champion, swept Simona Halep of Romania 6-0, 6-4.