French Open 2012: Azarenka and Sharapova through in Paris

World number one Victoria Azarenka reached the fourth round of the French Open with a straight-sets win over Aleksandra Wozniak.

The Belarussian booked a last-16 meeting against Dominika Cibulkova with a 6-4 6-4 victory over the Canadian.

However, Agnieszka Radwanska and Ana Ivanovic lost to Svetlana Kuznetsova and Sara Errani respectively.

Maria Sharapova continued her bid to complete the career Grand Slam with a simple win over Japan's Ayumi Morita.

Sharapova's second-round match was held over from Thursday after Paul-Henri Mathieu took almost six hours to beat John Isner in the men's draw.

But she wasted little time in breezing past the world number 84 6-1 6-1.

"Yesterday was one of those days where you just want to get on the court and then, you're hanging around all day, sitting, waiting around, eating, sleeping. It's like a good way to put someone into retirement," said the Russian.

"It was nice to get out there today and finish it."

Sharapova will play Chinese Peng Shuai in the third round.

Azarenka was in danger of seeing her match held over until Saturday, but when it became clear that it would be unable to played on Court Suzanne Lenglen on Friday, it was switched to Court One.

The Australian Open champion was challenged by Wozniak, but secured the first break in the ninth game of the first set to take the lead.

The pair traded breaks early in the second set, before Azarenka went ahead in the seventh game and, after wasting a match point on Wozniak's serve, made no mistake on her own to advance to a tie against 15th seed Cibulkova, who was an easy winner over Maria Jose Martinez Sanchez.

Third seed Radwanska, conqueror of Venus Williams in round two, was beaten 6-1 6-2 by 2009 champion and 26th seed Kuznetsova.

"I have not had this feeling for quite a time," said Kuznetsova. "I have started to do things the right way off the court in practice. I am confident I am getting back to my game that brought me the victories I had."

Number 21 seed Ivanovic, Roland Garros winner in 2008, went down 1-6 7-5 6-3 to Errani.

The former world number one, coached by Briton Nigel Sears, committed 37 of her 40 unforced errors in the final two sets.

"In the third set I was creating a lot of opportunities and missing a lot of easy, easy finishing balls," said Ivanovic. "That's something that I'm not really happy about."

Italian 13th seed Errani, in what will be her first appearance in the French Open fourth round, meets Kuznetsova for a place in the last eight.

Sixth seed Samantha Stosur went through with few problems, defeating Nadia Petrova of Russia 6-3 6-3.

The Australian will play 19-year-old American Sloane Stephens for a place in the quarter-finals.

Stephens, who beat Mathilde Johansson, the last Frenchwoman in the draw, 6-3 6-2 is the last American in the women's draw.

It is the first time she has reached the last 16 of a Grand Slam tournament in four appearances.