Ammon News - (Reuters) - Serena Williams heads to Wimbledon to defend her title with seeds of doubt and defeatism already sown in the minds of her opponents.

The psychological scars of playing the younger Williams sister run deep in the women's game and, now that the American has dusted off the red clay from her shoes, predictions of an upset on southwest London's luscious lawns are few and far between.

Having bludgeoned her way to a 16th grand slam and second title at Roland Garros, Williams can now tighten her grip still further on the sport she has come to dominate by claiming a fourth major in five attempts.

Few rivals

It is little wonder then that Williams's rivals for the Wimbledon title can realistically be counted on one hand.

Her opponent in the final at Roland Garros, Maria Sharapova, and Belarussian world number two Victoria Azarenka are the leading candidates to throw a spanner in the works.

Confidence, however, is hardly overflowing.

Sharapova was circumspect to say the least on entering the French Open final having lost 12 consecutive matches to Williams.

"I'd be lying if I said it doesn't bother me, obviously," the Russian said of a losing record stretching back to 2004.

Defeat in the quarter-finals of the Australian Open in January is the only smudge on a near-perfect year in which Williams has returned to the pinnacle of the rankings and re-conquered Paris, where the title had eluded her since 2002.

Back then she went on to complete the "Serena Slam", winning all four majors consecutively and few would bet against her repeating the trick.

She is on a 31-match winning streak with a 75-4 win-loss record in the past 12 months and has the added comfort of knowing that her game is ideally suited to the All England Club where her huge serve and heavy hits skid through with a little extra fizz.

Petra Kvitova, 2011 Wimbledon champion, is not the first to suggest that Serena's biggest opponent is frequently herself.

"I think that the players have to play 100 per cent and to play really, really well. Serena sometimes doesn't have a great day but she's still able to beat the other players," she told Reuters.

Few chances

World number five Sara Errani, who was on the receiving end of one of Williams's most emphatic maulings in the semi-finals in Paris, losing 6-0 6-1, neatly summed up the sense of foreboding.

"You have to have one of your best days and try to think she can have one bad day," she said.

At 31, Williams is already the oldest woman to win a major since Martina Navratilova claimed a ninth Wimbledon singles title in 1990.

She needs two more to draw level with both Navratilova and Chris Evert who sit above her with 18 major titles on the all-time women's list headed by Margaret Court with 24.

While the ultra-competitive men's game holds few parallels with the Williams-dominated women's, the American needs one more grand slam to draw level with Roger Federer, often hailed as the greatest player to pick up a racket.

"She's playing the best tennis of her career, mentally she's in the best place I've ever seen her," three-times men's champion John McEnroe said during a conference call organised by ESPN.

"She is the best player that ever lived. She's a level above anyone - there's no doubt about it.

"Serena is one of the greatest athletes in the history of our sport, male or female. She has such an intimidation factor it will be difficult for anyone to beat her."

Older sister Venus, who won the last of her five Wimbledon titles in 2008, has pulled out this year with a back injury, and among the rest the title credentials are flimsy.

Sharapova has reached only one Wimbledon final since winning it as 17-year-old in 2004 while Azarenka has fallen at the semi-final stage in the last two years and has enjoyed grand-slam success only in Australia.

Last year's surprise finalist Agnieszka Radwanska is playing down her hopes of going one better.

"There's always a bit of pressure when you are defending a final (appearance) but I'm just trying not to really think about it, just enjoying playing on grass, enjoying Wimbledon - it's my favourite grand slam."