Serena Williams announced Friday that she has pulled out of two forthcoming tournaments in China citing an ongoing shoulder injury.
"I am disappointed that I will not be able to compete at the Dongfeng Motor Wuhan Open or the China Open due to continuing issues with my right shoulder," Williams said in a statement.
"I have been practicing and playing but my shoulder is still not fit for tournament play," she added.
Williams has not been seen on court since the US Open earlier this month, where she was knocked out by Czech Karolina Pliskova in the semi-finals and lost her long-held position as world number one to eventual champion Angelique Kerber.
Williams, 34, also withdrew from two tournaments with a shoulder injury in July, after successfully defending her title at Wimbledon.
Shoulder problems also hampered her in Rio, where her hopes of a fifth Olympic gold medal were crushed in the third round by Ukraine's Elina Svitolina.