World number one Serena Williams was forced to pull out of her Hopman Cup encounter earlier today because of a knee complaint.
The American had been due to face Ukraine's Elina Svitolina at the Perth-based tournament.
However, having suffered with some inflammation to the joint during a recent training session, Williams decided to withdraw and was replaced by Vicky Duval.
It is not expected that the problem will prevent the 34-year-old from defending her Australian Open title later this month.
