Maria Sharapova and Victoria Azarenka both bludgeoned their way through to the last 16 of the French Open on Saturday as the sun finally returned to Roland Garros and the noise levels went up.

Defending champion Sharapova was given a scare by China's Zheng Jie, recovering from a 4-1 deficit in the second set to win 6-1 7-5, while third seed Azarenka was pushed even harder before winning a three-setter against Frenchwoman Alize Cornet.

Azarenka's 4-6 6-3 6-1 victory put her on collision course with former champion Francesca Schiavone who ended the hopes of another home favourite with a 6-2 6-1 beating of Marion Bartoli.

With women's favourite Serena Williams enjoying a day off after motoring through to the last 16 on Friday, two American women took their chance to grab some of her limelight.

Sloane Stephens, 20, emulated her run to last year's fourth round with a three-set victory over New Zealand's Marina Erakovic, while unseeded Bethanie Mattek-Sands also survived a three-setter against Argentine Paula Ormaechea.

While Sharapova always looked capable of turning around her second-set deficit against Zheng, Azarenka looked in more trouble as she was knocked off her stride by Cornet.

Belarussian Azarenka, the Australian Open champion, eventually found her range to keep her challenge for a first French Open title on course.

"She's a machine, a juggernaut," Cornet told reporters. "She plays the same from the first to the last point."

Sharapova afterwards called for HawkEye to be used after being on the wrong end of a dubious call in her victory.

Sharapova said: "It's not even about the fact of the call, whether it was in or out.

"I think for me it was the fact that the umpire did not recognise that the mark he pointed out was about a foot away from the actual mark. So that's a huge question mark, to begin with.

"All the other grand slams have HawkEye. And I know these types of situations, although much more rarely on the clay, happen. Why not? Why don't we have a system like this? Is it a money concern? I don't think so.

"This is just absolute proof that it's a big point and it can happen in any situation. So I hope he (Joseph) is able to acknowledge that that was not the right thing to say."