Former world number one Serena Williams has pulled out of next month's Hopman Cup team event.

Williams told organisers of the Perth event that she wants to concentrate on defending her title at the Australian Open in Melbourne which begins on January 19.

The world number three, the winner of six Grand Slam titles, will be replaced in the U.S. Hopman Cup team by Lindsay Davenport, tournament director Paul McNamee told reporters on Monday.

World number five Davenport will partner James Blake for the defending champions at the January 3-10 team event.

"Serena regrets not being able to come back and defend her title but we have a wonderful replacement in Lindsay Davenport," said McNamee, who is also an Australian Open director.

The United States remain the top seeds ahead of Australia despite the loss of Williams.

Neither Williams nor her elder sister Venus have played since Wimbledon, in July, a championship Serena won.

Serena, 22, had knee surgery in August. Venus is planning to return in Melbourne after a long lay-off with an abdominal tear.

The Australian Open will mark the first tournament appearance for Serena and Venus since their sister Yetunde Price was shot dead in a Los Angeles suburb in September.