Serena, Venus advance; Radwanska, Wozniacki exit Rome

Last week's Madrid titlist Serena Williams and her older sister Venus advanced, while world No. 3 Agnieszka Radwanska and former No. 1 Caroline Wozniacki went by way of the upset Wednesday at the $2.168 million Italian Open tennis event, a clay-court French Open tune-up.

The ninth-seeded former No. 1 Serena had to come from behind to best former top-10 Russian Nadia Petrova 4-6, 6-2, 6-3 in 2 hours, 9 minutes on the red clay at Foro Italico.

The 2002 Rome champion Serena, now 15-0 on clay this year, upset current world No. 1 Victoria Azarenka in last week's finale on the controversial blue clay in Madrid.

Up next for the powerful American will be Spaniard Anabel Medina Garrigues.

The wild card Venus, meanwhile, also topped a Russian opponent on Day 3, Ekaterina Makarova, 7-6 (9-7), 6-1 to setup a third-round match with Samantha Stosur, who stunned Serena in last year's U.S. Open finale.

Venus was the Rome champion in 1999 and runner-up in 1998.

Radwanska succumbed to Czech Petra Cetkovska 6-4, 4-6, 6-1 and the sixth- seeded Wozniacki gave way to the clay-court specialist Medina Garrigues 6-4, 4-0, as the Danish star retired due to upper respiratory illness.

A fifth-seeded Stosur avoided an upset by handling Italian crowd favorite Sara Errani 6-3, 7-5. Stosur was last year's Italian Open runner-up to former No. 1 Maria Sharapova.

Eighth-seeded reigning French Open champion Li Na, of China, got past Czech veteran Iveta Benesova 6-1, 7-5, while another upset came when capable German Julia Goerges drubbed seventh-seeded Frenchwoman Marion Bartoli 6-3, 6-1.

In other second-round action involving seeds, No. 12 German Angelique Kerber whipped American Vania King 6-3, 6-2, No. 13 Ana Ivanovic pasted Spanish qualifier Silvia Soler-Espinosa 6-1, 6-2, and No. 14 Slovak Dominika Cibulkova edged out Italian wild card Karin Knapp 6-3, 4-6, 6-1. Up next for the former French Open champion Ivanovic will be her fellow former No. 1 Sharapova.

South African Chanelle Scheepers overcame New Zealand's Marina Erakovic 5-7, 6-1, 6-2, while Italian favorite Flavia Pennetta dismissed American qualifier Sloane Stephens 6-2, 6-3, and Romanian Sorana Cirstea leveled Swede Sofia Arvidsson 6-3, 6-1 in some other second-round play.

The 2012 Rome titlist will collect $385,000.