Victoria Azarenka is set to miss the US Open because she is "not willing" to leave her child at home in California.
The Belarusian former world number one returned to tennis in June after giving birth to her son, Leo, in December.
Azarenka, 28, separated from his father in July and the pair are working "to resolve some of the legal processes".
In a statement, Azarenka said: "The way things stand now is that the only way I can play in the US Open this year is if I leave Leo behind."
The US Open gets under way in New York on 28 August.