Red-hot Serena Williams posted an opening-round win Tuesday at the $2.05 million Western & Southern Open, a U.S. Open Series event, while Maria Sharapova easily advanced to the third round.

The former world No. 1 Williams notched her 12th straight match victory with a 6-3, 7-6 (7-5) decision against Czech Lucie Hradecka on the hardcourts at the Lindner Family Tennis Center. Williams fired seven aces in the 1-hour, 39- minute win.

The 13-time Grand Slam champion Williams is seeking her third title in three events, having titled in Toronto last week and Stanford last month.

Next up for the American great will be Aussie Samantha Stosur, who lost to Williams in this past Sunday's finale in Toronto.

The fourth-seeded Sharapova needed just 71 minutes to defeat Anastasia Rodionova, 6-1, 6-3. Sharapova was last year's Cincy runner-up to Kim Clijsters.

Additionally, fifth-seeded Li Na moved into the third round with a 6-3, 6-4 handling of Czech Lucie Safarova. The Chinese Li captured this year's French Open title and was January's runner-up to Clijsters at the Australian Open.

In other second-round action, sixth-seeded Czech Petra Kvitova moved on with a 7-6 (7-3), 6-3 defeat of South African Chanelle Scheepers. Kvitova upset Sharapova in last month's Wimbledon final.

Eighth-seeded Marion Bartoli of France also reached the third round with a 6-1, 6-2 rout of the Ukraine's Alona Bondarenko.

Last week's Toronto runner-up to Williams, the 10th-seeded Stosur, reached the second round this week with a 6-3, 6-1 pasting of Greek qualifier Eleni Daniilidou.

In other opening-round play involving seeds, Italian Flavia Pennetta dismissed No. 12 Anastasia Pavlyuchenkova of Russia 2-6, 6-3, 6-3, No. 13 Jelena Jankovic whipped Czech Iveta Benesova 6-0, 6-3, No. 16 Peng Shuai of China got past Argentine Gisela Dulko 6-3, 4-6, 6-4, and No. 17 Yanina Wickmayer of Belgium decked Serbian qualifier Bojana Jovanovski 6-3, 6-4. The former world No. 1 and former U.S. Open runner-up Jankovic was the Cincy champion two years ago.

Additional opening-round wins came for Russians Nadia Petrova and Maria Kirilenko.

This week's top seeds are world No. 1 Caroline Wozniacki and 2010 U.S. Open runner-up Vera Zvonareva.

The 2011 Cincinnati champion will collect $360,000.