Madrid, Spain (SportsNetwork.com) - Reigning world No. 1 Serena Williams and former top-ranked star Caroline Wozniacki were a pair of easy second-round winners Monday at the Madrid Open tennis event.

The Australian and U.S. Open titlist Williams eased past fellow American Sloane Stephens 6-4, 6-0, while the fifth-seeded U.S. Open runner-up Wozniacki handled American qualifier Christina McHale 7-5, 6-0 on the red clay at the Magic Box.

Williams, who captured back-to-back Madrid titles in 2012 and 2013, has yet to lose this year, going 22-0. She's won her last 25 matches overall, dating back to November.

In other action involving seeds, No. 9 Pole Agnieszka Radwanska whipped Aussie Casey Dellacqua 6-2, 6-1, Romanian Irina-Camelia Begu moved on past No. 11 German Andrea Petkovic via walkover and No. 13 Czech Lucie Safarova drilled Bulgarian Tsvetana Pironkova 6-3, 6-1 at this French Open tune-up.

The former Wimbledon runner-up Radwanska will battle the 2009 Madrid runner-up Wozniacki in the round of 16.

Also on Day 3, Italian Roberta Vinci beat France's Alize Cornet 6-4, 7-5, two-time Grand Slam champion Svetlana Kuznetsova snuck past rising Spaniard Garbine Muguruza 6-3, 5-7, 7-5 and former U.S. Open champ Samantha Stosur doused Estonian Kaia Kanepi 6-3, 6-2.

Several stars will see second-round action on Tuesday, including third-seeded former No. 1 and reigning Madrid champ Maria Sharapova, fourth-seeded Petra Kvitova, seventh-seeded former top-ranked performer Ana Ivanovic, and unseeded former No. 1 and two-time Madrid runner-up Victoria Azarenka.

The French Open champion Sharapova topped Simona Halep in last year's Madrid finale and was the 2013 runner-up here to Williams.

Kvitova was the Madrid champ in 2011.