Williamses' court-craft key to their success

Movement and guile -- not just power -- puts the Williams sisters Venus and Serena head and shoulders above the rest of the world, says former top-ranked player Billie Jean King.

Venus defends her U.S. Open at Flushing Meadows next week as second seed, one place below younger sister Serena who is looking to add a second U.S. title to the French Open and Wimbledon crowns she has won this year.

But while much is made of the sisters' power, the secret of their success runs much deeper than that, according to U.S. Fed Cup captain King.

"It's the movement. It's not the power," King said after Wednesday's draw for the fourth and final grand slam of the year.

"Lindsay Davenport hits harder off the ground than they do, for instance. You have to have the movement to match them.

"You have got to break it down a little more specifically. Jennifer Capriati hits as hard off the ground as well.

"It is not just about power. It's a combination of things, power, finesse, movement, first serves.

"But it's all of those things, you have to break it down that way. But they have the combination that really makes the difference."