INDIAN WELLS, Calif. -- Top-ranked Elena Rybakina has withdrawn from the WTA Finals for medical reasons before the season-ending championships begin.

"I've had an incredible season, but my body is just not physically ready to compete," the 27-year-old said in a statement Saturday, a day before the event gets underway at Indian Wells Tennis Garden. "I'm going to spend some time resting and recovering at home and getting myself ready for the 2027 season."

Marta Kostyuk moves into the draw as the first alternate in Group 1, and she will open play Sunday against Wimbledon champion Linda Noskova. Americans Coco Gauff and Jessica Pegula meet in the day's other round-robin singles match.

Rybakina's withdrawal wasn't a surprise. She had pushed her pre-event news conference from Friday to Saturday and withdrew from last week's Pan Pacific Open quarterfinals in Japan with a neck injury.

Rybakina was the defending champion, having won last year in Saudi Arabia. She won the US Open in September and ascended to the No. 1 ranking.

She finishes the season with a 54-14 match record and four titles, including the Australian Open.