US Open champion Serena Williams has withdrawn from the Hopman Cup international mixed team tournament.

Tournament organizers have confirmed that Williams cannot recover from the hamstring injury she got from the WTA championships, in time for the Hopman Cup which kicks off on January 3. However, Williams said she still plans to compete in the Australian Open, which starts in January 19.

As for the other line-ups, Meghann Shaughnessy is paired with James Blake—the two have competed in same tournament in 2003. On the other hand, Marat Safina will partner with his sister Dinara Safina to complete the Russian team.