ESPN Tennis

PERTH, Australia -- U.S. Open champion Serena Williams has withdrawn from next month's Hopman Cup as she continues to recover from a hamstring injury.

Organizers announced Monday that Williams, No. 2 in the rankings, would not recover in time after she was injured at last month's WTA Championships. The Hopman Cup starts Jan. 3 but Williams still intends to play at the Australian Open starting Jan. 19.

Two-time champion James Blake will now be joined by Meghann Shaughnessy on the U.S. team in the mixed-team tournament. Williams and Blake combined to win the 2003 Hopman Cup.

Marat Safin has confirmed he will partner with his sister, Dinara Safina, for the Russian team.

Copyright 2008 by The Associated Press