MASON, Ohio — Serena Williams‘ opening match in the Western & Southern Open has been rescheduled from Monday to Tuesday.

The 40-year-old Williams, preparing to retire, is set to face 19-year-old Emma Raducanu, the defending US Open champion. A spokesperson for the tournament said the change was “on account of a number of factors related to scheduling.”

Williams has said she wants to have another child and pursue business interests. The 23-time Grand Slam champion has not said what her last event will be, but has made it sound as if her final farewell will come at the US Open, which begins Aug. 29 in New York.

Williams lost 6-2, 6-4 to Belinda Bencic on Wednesday night in Toronto in her first match since she elaborated on her future plans.