World number 19 Daria Kasatkina says she is at "breaking point" and has ended her season early, describing the schedule as "too much, mentally and emotionally".
The 28-year-old switched nationality from Russia to Australia in March, having criticised her country's LGBTQ+ laws and the war in Ukraine.
She struggled for form this year, failing to win a title and finishing with a 19-21 record.
Kasatkina said the emotional stress of her nationality switch contributed to her struggles, including not seeing her father for four years.
"I've been far from fine for a long time and, truth be told, my results and performances show that," she wrote in a lengthy statement.