The two sisters will again be absent when the elite, eight-woman WTA Tour Championships begin here on Wednesday.
But six-times Grand Slam champion Serena confirmed on Monday that she would play in the Hopman Cup mixed team event in Perth from January 3-10.
Venus, meanwhile, said she was targeting the Australian Open (January 19-February 1) in Melbourne for her first tournament back.
Reigning Australian Open and Wimbledon champion Serena underwent knee surgery in August. Venus has been nursing an abdominal tear since the All-England championships in July.
"I'm definitely planning on playing the Australian (Open)," Venus told reporters on Monday while refusing to commit to any warm-up events.
Serena said: "I'm going to play the Hopman Cup. I really enjoyed that last year."
Appearing at the annual WTA Tour Charities Gala and Fashion Show in Santa Monica, the Williams sisters said their minds did wander back to the court, even though they were deeply involved in the fashion show.
The show was directed by Serena and included several professional models and players including Venus, top-ranked Kim Clijsters, Jennifer Capriati, Elena Dementieva and Anastasia Myskina.
GREAT ATMOSPHERE
Venus reached the 2002 WTA Tour Championships semi-finals, losing to Clijsters, who went on to beat Serena in the final.
"We really miss being on the tour," Serena said. "It's such a great atmosphere, it's like one big family.
"Obviously I miss it a lot but don't want to dwell on it too much. Once I realised I couldn't play, I just got focused on doing the fashion show."
Venus, who first sustained her abdominal tear at a tournament in Warsaw in April, decided to withdraw from this week's event on Sunday.
"I'm disappointed I couldn't be in the championships but, the way I look at it, some things aren't meant to be," Venus said.
"I'm looking forward to starting up next year. I'm doing a lot better, I'm approaching the 90th percentile, but it took a lot longer than I ever imagined."
While ticket sales for the tournament are up on last year, other competitors realise it will not be easy to pack the arena this week without the Williams sisters, who grew up in nearby Compton.
"This tournament is so special that you want the best to be there," Clijsters said.
"Especially without Venus and Serena, it's a tough situation. It's not the same without them. I miss playing them."
Reigning French and U.S. Open champion Justine Henin-Hardenne agreed.
"The players miss them and the tournaments do for sure because they are doing a great job for women's tennis," Henin-Hardenne said.
