PERTH (REUTERS) - World No. 1 Serena Williams was ruled out of her opening match at the Hopman Cup mixed-team event in Perth on Monday because of inflammation of the knee, organisers said.
The 34-year-old was scheduled to play her first official match since the US Open last September for the United States in their round-robin tie against the Ukraine but pulled out after a morning warm-up at the venue.
"I'm disappointed to not take the court in Perth today," Williams said in a news release. "I had every intention to play this morning. Unfortunately, due to inflammation in my knee I need to rest and am confident to be out there against Aussie Gold tomorrow evening."
Williams, who is using the event as preparation for her tilt at a 22nd Grand Slam singles title at the Australian Open later this month, will be replaced in the US team by 20-year-old Vicky Duval.