Former world number one Victoria Azarenka has pulled out of the US Open due to an "ongoing family situation" that would have meant leaving her young son in California.

The Belarusian made it to the fourth round at Wimbledon on her first grand slam appearance after returning to action following the birth of her son Leo last December.

But after separating from Leo's father, Azarenka would have had to leave her son at home in order to compete at Flushing Meadows, with custody papers having reportedly been filed in Los Angeles.

"I am sadly unable to compete in this year's US Open due to my ongoing family situation that I am working through," said Azarenka - finalist at the US Open in 2012 and 2013 - in a statement.

"While I will dearly miss being in New York and playing in one of my favourite tournaments, where I have enjoyed some of the best moments in my career, I am already looking forward to being back next year."

Following Azarenka's withdrawal from the final grand slam tournament of the year, Japanese player Misa Eguchi has been added to the draw.