The demand for tickets to the U.S. Open are soaring after Serena Williams announced she's preparing to say goodbye to tennis.

In a first-person essay for Vogue, Williams said she is "evolving away" from the sport and instead choosing to focus on her family.

"I have never liked the word retirement," Williams wrote. "It doesn't feel like a modern word to me. Maybe the best word to describe what I'm up to is evolution. I'm here to tell you that I'm evolving away from tennis, toward other things that are important to me."

The article appeared to hint the upcoming U.S. Open tournament will be her last grand slam, fueling ticket sales.

Following her announcement, approximately 13,000 U.S. Open tickets were sold on Tuesday, tournament organizers told ABC News.

Of those tickets sold, nearly 4,500 were for the tournament's opening night, according to the United States Tennis Association, despite Williams not being guaranteed to play in that slot.

Williams has played tennis professionally since 1995 and is one of the most decorated tennis players of all time. She has taken home 23 grand slams -- one short of the record -- and four Olympic gold medals in her career and spent 319 weeks ranked No. 1 in the world.

While her next chapter is on the horizon, in her Vogue essay, Williams said she's still enjoying her sport.

"This sport has given me so much. I love to win. I love the battle. I love to entertain. I'm not sure every player sees it that way, but I love the performance aspect of it -- to be able to entertain people week after week ... Night matches in Arthur Ashe Stadium at Flushing Meadows. Hitting an ace on set point."

As she shifts to focus on motherhood and investing in a new part of herself, Williams wrote on Instagram: "My goodness do I enjoy tennis. But now, the countdown has begun ... I'm gonna relish these next few weeks."