Mason, OH (Sports Network) - World No. 1 Serena Williams needed all three sets to win her second-round match Wednesday at the $2.37 million Western & Southern Open, a hardcourt U.S. Open tune-up.

Following an opening-round bye, the reigning U.S. and French Open champion lost the opening set against rising Canadian Eugenie Bouchard before charging back for a 4-6, 6-2, 6-2 decision at the Lindner Family Tennis Center. The American needed 1 hour, 47 minutes to advance, which she did with the help of seven aces and six breaks of serve.

Meanwhile, sixth-seeded former French Open runner-up Sara Errani of Italy snuck past Slovenian Polona Hercog 6-4, 5-7, 6-4 and 11th-seeded former U.S. Open champion Samantha Stosur of Australia handled American Jamie Hampton 6-3, 7-6 (7-3). Stosur was the titlist in Carlsbad two weeks ago.

Also on Day 3, 12th-seeded Italian Roberta Vinci held off resurgent German Andrea Petkovic, 6-4, 6-7 (3-7), 6-3.

This week's winner will earn $426,000. The tournament is part of the U.S. Open Series, or the North American hardcourt events that lead up to the U.S. Open, which will commence August 26.