Defending Wimbledon champion Serena Williams has challenged her rivals to match her astonishing run of form as she targets a sixth All England Club title and 17th major.

The American, fresh from her second French Open triumph, is on a 31-match winning run, the best of a career that is already comfortably into its third decade.

She is now just two Grand Slam titles behind the 18 won by Chris Evert and Martina Navratilova and four back from the 22 racked up by Steffi Graf, but believes her best years may still be ahead of her.

"I'm really relaxed. I really enjoy every moment that I'm out there. I always said that I felt like I have never played my best tennis," said 31-year-old Williams, who became the oldest Roland Garros winner in the Open era when she beat Maria Sharapova in the final earlier this month.

"I feel like I can always do better and play better and I have always wanted to reach that level. Maybe I'm just trying to get there."

"I really believe age is a number at this point, because I have never felt so fit. I feel great. I look great."

The statistics back up Williams' confidence concerning her future prospects.

Agence France-Presse