How much is Serena Williams worth as she announces retirement plans?

American tennis great Serena Williams on Tuesday announced that her incredible career is coming to an end.

The 40-year-old is one of the greatest players in the history of tennis and hinted at finishing her storied career at the US Open which begins later this month.

"There comes a time in life when we have to decide to move in a different direction," she said on Instagram. "That time is always hard when you love something so much. My goodness do I enjoy tennis.

"But now, the countdown has begun. I have to focus on being a mom, my spiritual goals and finally discovering a different, but just as exciting Serena. I'm gonna relish these next few weeks."

It has been a challenging few seasons for Williams after she suffered a torn right hamstring at Wimbledon last year. On Monday, she competed in her first hardcourt match in 18 months, defeating Spain's Nuria Parrizas Diaz in Toronto.

She remains one shy of the all-time record of 24 Grand Slam singles titles won by Margaret Court. Williams won the last of her 23 Slams at the 2017 Australian Open.

"I have never liked the word retirement. It doesn't feel like a modern word to me," Williams wrote in Vogue as she revealed her retirement plans. "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.

"Unfortunately I wasn't ready to win Wimbledon this year. And I don't know if I will be ready to win New York. But I'm going to try."

Irrespective of what happens over the coming weeks, Williams will be celebrated as an inspirational figure in tennis who dominated the sport, alongside sister Venus, like very few before her.

Her incredible success and popularity amassed her