Five-time Grand Slam champion Maria Sharapova says she is "working through some painful days", after withdrawing from next month's BNP Paribas Open in Indian Wells, California.
The 31-year-old, who has a shoulder injury, has withdrawn or retired from two out of the three events she has played in since September's US Open.
"It's been an issue last year and going into this year," said the Russian.
"My doctor says it's a day-by-day pain management situation."
Sharapova beat defending champion Caroline Wozniacki to reach the fourth round of the Australian Open in January before losing to Ashleigh Barty.