Venus (left) and Serena Williams celebrate after defeating Ai Sugiyama and Katarina Srebotnik in a doubles match at the Australian Open earlier this year. They'd love to win Wimbledon, and Venus and Serena Williams will be among the favourites when the tournament begins on Monday. - AP

WIMBLEDON, England (AP):

THE INJURIES and intrigue, passion for fashion, disdain for the tennis grind and insistence on go-for-broke strokes - all in the context of a friendly sibling rivalry - make even mom reluctant to predict what the Williams sisters might do next.

They'd love to win Wimbledon, and Venus and Serena Williams will be among the favourites when the tournament begins on Monday. But both have been erratic this year, raising anew questions about their devotion to a sport they once dominated.

"They have a lot of things going on with their life," said their mother and coach, Oracene Price. "Sometimes you never know what's going on in their head, especially girls."

Rare double defeat

The sisters are coming off a rare double defeat at the French Open, where they were eliminated in the third round. It was only the second time they lost on the same day at a Grand Slam event, which should stoke their desire for a strong showing at Wimbledon.

"We always learn and get more determined after a loss," Venus said.

Grass often puts extra spring in their step. They've combined to win six of the past eight Wimbledon titles, and a return to the All England Club rejuvenated Venus' game last year, when she won the championship for the fourth time and became the tournament's lowest-ranked champion at No. 31.

Reason for success

On the surface, it's easy to explain the sisters' success at Wimbledon: Lawn tennis suits their big serves, slam-bang groundstrokes and willingness to charge the net.

In addition, they find inspiration in the tradition that accompanies their sport's oldest tournament.

"Wimbledon, I think, has been around for hundreds of years," Serena said. "It doesn't get better than that."

It has actually been around since 1884, when another family dominated. Maud Watson beat sister Lilian in the final.

More than a century later, the world's oldest and most tradition-bound tennis tournament is in transition. A retractable roof over Centre Court is still a year from completion but an overhead cover for fans is back after ongoing construction left them with no protection last year. Capacity has increased to 15,000 from 13,800.

Some good news

A new Court Two is nearly finished and the old one will be used this year for the last time. That's good news for such players as the Williams sisters, because Court Two has long been nicknamed the 'Graveyard of Champions'.

There are plenty of candidates to derail the sisters' title hopes this year, including French Open winner Ana Ivanovic, 2004 Wimbledon champion Maria Sharapova and 2006 winner Amelie Mauresmo.