Wimbledon 2013: Serena Williams aims for sixth All England Club title and 17th grand slam

Serena Williams

If trying to stop Serena Williams was not hard enough for the rest of the Wimbledon field, the defending champion has got a secret weapon in her corner.

Live blog: Click here for game-by-game coverage as Laura Robson attempts to reach the quarter-finals with a victory over Kaia Kanepi followed by Andy Murray against Mikhail Youzhny

The American is bidding for a sixth All England Club title and a 17th grand slam overall - something which looks to be nailed on after another all-conquering first week.

Tougher tests do lie ahead for the 31-year-old but she is ready to unleash double-trouble on her rivals owing to advice from sister Venus.

Herself a five-time Wimbledon winner, Venus Williams is missing through injury this year but has been texting her sibling advice on how to deal with opponents.

"She's sent me tons and tons of tips," Serena Williams said after beating Kimiko Date-Krumm.

"She sent me what to expect, what to do. She's so positive and I take that on court with me."

Serena Williams will face Sabine Lisicki in the fourth round today but fired an ominous warning to the German by adding of her form: "I'm getting there and am starting to feel better."

It will be difficult to find anyone to tip Lisicki against Williams, but having beaten Maria Sharapova against the odds 12 months ago, the she fancies her chances.

"I was in that situation last year when everyone was saying that Sharapova was the favourite. I'm going in as the underdog and I like that. I have nothing to lose," Lisicki said.

The 2011 champion, Petra Kvitova, is hoping that she can get the better of her inconsistencies against Carla Suarez Navarro.

The Czech's title defence ended at Williams' hands last year but she looks in good touch this time around.

She believes she still has it in her to falter, though, and wants to make sure she does not.

"I know I can drop off a little bit, I am always up and down but I hope I will be more up than down," she said.

"Carla is from Spain, she plays well on the grass and it will be very difficult for me."

Another player to have fallen to Williams last year is Agnieszka Radwanska, who made it all the way to the final.

She has been impressive so far and did well to come through a tough-looking clash with the up-and-coming Madison Keys on Saturday.

Her form is similar to that of compatriot Jerzy Janowicz in the men's draw and she is pleased to see Polish tennis riding high at Wimbledon.

"I think Polish tennis is getting bigger all the time and I am happy about that," she said.

Beneath the usual suspects there is a growing army of wannabes who are starting to make a name for themselves.

Depending on your nationality either Laura Robson or Sloane Stephens is the ringleader, with the former carrying British hopes against Kaia Kanepi and the latter taking on another young gun in the shape of Monica Puig.

Robson and Puig are 19 and Stephens is 20, and the American is set for the challenge ahead.

"When you are playing someone the same age as you it's tough," she said.

"Monica has a good technique, I do, Laura does. We all have a pretty good one and it's going to be hard."

Elsewhere today, the number 20 seed, Kirsten Flipkens, takes on Flavia Pennetta, France's Marion Bartoli goes up against Karin Knapp and Roberta Vinci takes on Li Na.

Live blog: Click here for game-by-game coverage as Laura Robson attempts to reach the quarter-finals with a victory over Kaia Kanepi followed by Andy Murray against Mikhail Youzhny

PA