Madrid, Spain (SportsNetwork.com) - Two-time champion Serena Williams and reigning titlist Maria Sharapova were a pair of quarterfinal winners Thursday at the Madrid Open tennis event.

The world No. 1 Williams whipped 10th-seeded Spaniard Carla Suarez Navarro 6-1, 6-3 on the red clay at the Magic Box.

The 33-year-old Williams, who captured back-to-back Madrid titles in 2012 and 2013, still has yet to lose this year, going 24-0, and the powerful American has won her last 27 matches overall dating back to November.

This is the second-longest winning streak of her career. She won 34 in a row in 2013.

Williams is playing in only her third WTA tournament since clinching her sixth Australian Open title and 19th Grand Slam singles championship in January.

Meanwhile, the third-seeded Sharapova, who's chasing an 11th career title on clay, held off fifth-seeded fellow former world No. 1 Caroline Wozniacki 6-1, 3-6, 6-3 on Day 6.

Sharapova is now 6-4 lifetime against Wozniacki, who had won their previous two meetings.

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

Wozniacki was a Madrid runner-up in 2009.