World No. 2 Serena Williams withdrew from the BNP Paribas Women's Tennis Association Finals in Singapore after receiving advice from her doctors regarding a shoulder injury. The 22-time Grand Slam champion made the announcement on Monday.

“Everyone in Singapore and all my fans in Singapore, I'm really really bummed that I won't be able to come compete this year...It's been a tough year for me, just dealing so much with the shoulder injuries. My doctor insists I stay home and heal it every single day and do different treatments so I can play next year and hopefully play in Singapore next year. I think that would be my biggest goal...I had so much fun there and I have only wonderful memories playing in Singapore," said Williams.

"I was looking forward to competing in Singapore this year and playing against the best players in the world," said Williams. "However, I have received disappointing news from my doctor that I must undergo a series of medical treatments for my shoulder, and will be off the court for the next several weeks. I will miss coming to Singapore for the year-end Finals and playing in front of my fans, but truly hope to be back soon."

Williams has participated in eight tournaments this season, winning two titles at the Internazionali BNL d'Italia and Wimbledon. She also reached the finals of the Australian Open and French Open.

Angelique Kerber, Simona Halep, Agnieszka Radwanska, Karolina Pliskova and Garbiñe Muguruza, Madison Keys and Dominika Cibulkova have already qualified for the tournament, which starts on October 23 and ends on October 30.