Wimbledon 2013: Serena Williams criticised by Maria Sharapova

Maria Sharapova believes rival Serena Williams should not comment on matters outside of tennis as she criticised the American ahead of Wimbledon.

Defending Wimbledon champion Williams was forced to apologise for what she was reported to have said about the rape of a 16-year-old girl in Ohio.

"I was sad to hear what she had to say about the whole case," Sharapova said.

Williams beat Sharapova in this year's French Open final and the pair cannot meet at Wimbledon until the decider.

The Russian also spoke about a reported relationship between Williams and her French coach Patrick Mouratoglou after the American tennis star appeared to criticise Sharapova in the same article published in Rolling Stone magazine.

"I just think she should be talking about her accomplishments, her achievements, rather than everything else that's just getting attention and controversy," the Russian former world number one said.

"If she wants to talk about something personal, maybe she should talk about her relationship and her boyfriend that was married and is getting a divorce and has kids.

"She has so much in her life, many positives, and I think that's what it should be about."

The French coach and Williams have not confirmed the nature of their relationship, and there has been no confirmation that his marriage has ended.

Williams released a statement on Wednesday apologising for the comments regarding the rape case in Steubenville, Ohio which appeared in Rolling Stone magazine after they caused controversy.

"I am currently reaching out to the girl's family to let her know that I am deeply sorry for what was written in the Rolling Stone article," Williams said in a statement.

"What was written - what I supposedly said - is insensitive and hurtful, and I by no means would say or insinuate that she was at all to blame."

Sharapova insists she prefers to keep private matters to herself and to only discuss her career with the media.

"I obviously have many opinions about different things in life," Sharapova, who has her own social media channel on Facebook, added.

"But what I do on the court and what I talk about in my press conference is strictly about my career. I'm sure people want to know more, but yet I try to keep my personal life private.

"If I speak to my friends, that's one thing. But I don't go out and try to create things that shouldn't be really talked about."

Number one seed Williams, a 16-time Grand Slam winner, will begin her bid for a sixth Wimbledon title against Mandy Minella on Tuesday.

Third seed Sharapova, who won her sole Wimbledon title as a 17-year-old in 2004, will open her campaign against 20-year-old Kristina Mladenovic of France, the world number 39, who won her first WTA title at the Taipei Open last year.