Cape Town - Serena Williams is set to face Roger Federer in her first event of the 2019 season when the USA play Switzerland in the mixed doubles at the Hopman Cup.
Williams, 37, has not played since her controversial US Open final defeat by Naomi Osaka in September.
According to the BBC website, the 23-time Grand Slam champion partners Frances Tiafoe, while 20-time Grand Slam winner Federer and Belinda Bencic will seek to defend their title.
"The Aussie fans are always so warm and supportive and the Hopman Cup has always given me a great start to the season, especially ahead of the Australian Open," said Williams, who pulled out of this month's China Open.
Williams will be playing in Australia for the first time since winning the 2017 Australian Open while eight weeks pregnant, having missed last year's tournament as she was not fully fit to return following the birth of daughter Olympia.
The Hopman Cup runs from December 29 until January 5, with the 2019 Australian Open taking place from January 14-27.
The mixed team event features eight nations split into two groups, with teams facing each other in sessions that consist of a men's and women's singles match and a mixed doubles match.
France - Lucas Pouille and Alize Cornet
Spain - David Ferrer and Garbine Muguruza
Germany - Alexander Zverev and Angelique Kerber
Australia - Matt Ebden and Ashleigh Barty
Great Britain - Cameron Norrie and Katie Boulter
Greece - Stefanos Tsitsipas and Maria Sakkari
Switzerland - Roger Federer and Belinda Bencic
USA - Frances Tiafoe and Serena Williams