World No.2 Serena Williams will not take part at BNP Paribas WTA Finals Singapore presented by SC Global after receiving medical advice regarding a troublesome shoulder injury.

The 35-year-old 22-time Grand Slam champion made the announcement late on Sunday after missing all of the Asian Swing due to that same issue; shoulder problems also kept her out of the Rogers Cup and Western & Southern Open earlier in the summer.

“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, where she tied Stefanie Graf for the Open Era record of Grand Slam titles. She also reached the finals of the Australian Open and French Open, and tied Graf for the all-time record of most consecutive weeks at World No.1, at 186 straight weeks.

“We’re as disappointed as the fans not to see Serena finish her season in Singapore,” says WTA CEO Steve Simon. “We wish her a speedy recovery and look forward to seeing her back competing, fit and healthy.”

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.