Serena Williams of the US reaches out to return a forehand to Peng Shuai of China during their match at Madrid Open tennis tournament in Madrid May 7, 2014. [Photo/Agencies]

MADRID - Serena Williams and Rafael Nadal breezed into the Madrid Open third round with their title defenses facing little strain on Wednesday, while Andy Murray made a successful return to clay after nearly a year's absence.

Williams broke Peng Shuai three times in a 6-2, 6-3 win that was her 14th straight on the clay of the Magic Box tennis center, where the top-seeded American dominated her Chinese opponent on serve by firing 11 aces.

Williams, who moves on to face Spanish player Carla Suarez Navarro, looked fresh and focused while dismissing any injury fears despite a heavily wrapped left leg.

"I just had some issues and went preventive to make sure I didn't make anything worse," said Williams. "I'm literally taking it one day, one match at a time, and not putting any pressure on myself."

In other women's results, third-seeded Agnieszka Radwanska of Poland and No 4 Simona Halep of Romania both advanced, while Roberta Vinci of Italy knocked out Caroline Wozniacki 6-3, 6-3.

Related: Li, Radwanska reach 2nd round at Madrid Open