The draw Saturday placed top-seeded Williams in the Red Group with 23-year-old Simona Halep and 20-year-old Canadian Eugenie Bouchard as well as the more experienced Ana Ivanovic, who has beaten the American only once in eight matches.
"I don't care who I play, to be perfectly honest with you. You can put me against anybody at this point, I'm ready," said the top-ranked Williams, whose appearance in Singapore was in doubt after she pulled out of the China Open tournament earlier this month with a knee injury. "I really can't wait for my match. I wish I had a match tomorrow."
Bouchard, from Westmount, Que., is playing in the event for the first time.
The tournament starts Monday at the 10,000-capacity Singapore Indoor Stadium. The 33-year-old Williams won this year's U.S. Open and has won the past two WTA finals.
The White Group sees second-seeded Maria Sharapova, the French Open champion, joined by Wimbledon winner Petra Kvitova, Caroline Wozniacki and Agnieszka Radwanska.
"I'm quite happy with my group," said Sharapova, who is coming into the tournament after winning the China Open.
"I think every match will be a challenge. There are some players that I've lost to this year, and some players that I beat, so it's a little bit of everything. I hope to start on a good note."
Denmark's Wozniacki has had a resurgent season, climbing back inside the world's top 10 and reaching her second US Open final before losing to Williams.
"I'm just excited to be here. It's tough competitors I'm against. I'm looking forward to the challenge and getting some great matches."
Third-ranked Halep is in search of her first major title after making several semifinals this year.
"It's not an easy draw," said the Romanian. "But everyone here is strong and a great player. I'll enjoy my matches and try my best to win"
The draw was made at a shopping mall.