Madrid, May 5 (IANS): World number one Serena Williams needed less than an hour on Monday to get her campaign for the Mutua Madrid Open off to a comfortable start with a 6-4, 6-0 win over fellow American Sloane Stephens, media reported on Tuesday.

Williams, despite a slow start, soon found her rhythm and Stephens had no answer to her power on the beaten clay of the Caja Magica center court, Xinhua reported.

Williams was joined in the second round by number five seed, Caroline Wozniachi, who nevertheless needed an hour and a half to dispatch qualifier Christina McHale 7-5, 6-0 after being made to dig deep in the first set which she won in the 12th game.

The morning saw good news for the womens' seeds as number 9 seed Agnieszka Radwanska needed just over an hour to win her match against Casey Dellaqua 6-2, 6-2, and 13th seed Lucie Safarova also had a sets (6-3, 6-1) win over Tsevlana Pironkova.

The experienced Russian Svetland Kuznetsova had to dig deep against unfancied Spaniard, Gabine Muguruza, who raised her game with the support of the Madrid fans, but finally lost after 2 hours and 40 minutes, (6-3, 5-7, 7-5).

Australian, Samantha Stosur also booked her place in the next round thanks to a 6-3, 6-2 victory over Finland's Kaia Kanepi.

In the men's tournament, big-hitting number 16 seed, John Isner qualified in two sets, although he was made to work hard for his 7-6 (2), 6-4 win against France's Adrian Mannarino.

Meanwhile local favorite Feliciano Lopez had to work a lot harder to defeat Benjamin Becker 7-5, 3-6, 6-4.

The big serving left hander from Toledo is one of the few Spaniards who is happier on a fast court than on beaten clay, but he is helped by the altitude at Madrid which means the ball flies through the air faster than in many tournaments played at sea level.