(CNN) Serena Williams gave birth to her baby girl Alexis Olympia this month and as she adjusts to becoming a parent for the first time the tennis great has written a heartfelt letter to her own mother, Oracene Price.

Williams, 35, wrote of her admiration for her mom, for her strength in the face of those "too ignorant to understand the power of a black woman."

In the letter, the 23-time grand slam champion -- the most successful player in the Open Era -- talks of the criticism she has had to endure for her muscular physique and writes of her baby daughter's "same strong, muscular, powerful, sensational arms and body."

The American opens the letter by calling her mom "one of the strongest women I know."

Oracene Price is a familiar figure at grand slams when her daughers are playing.

'We are women and proud'

"I was looking at my daughter (OMG, yes, I have a daughter) and she has my arms and legs!" Williams says in the letter first published on reddit, the site co-founded by her fiance Alexis Ohanian.

"I don't know how I would react if she has to go through what I've gone through since I was a 15-year-old and even to this day.

"I've been called man because I appeared outwardly strong. It has been said that that I use drugs (No, I have always had far too much integrity to behave dishonestly in order to gain an advantage).

"It has been said I don't belong in Women's sports -- that I belong in Men's -- because I look stronger than many other women do. (No, I just work hard and I was born with this badass body and proud of it).

"But mom, I'm not sure how you did not go off on every single reporter, person, announcer and quite frankly, hater, who was too ignorant to understand the power of a black woman.

"I am proud we were able to show them what some women look like. We don't all look the same. We are curvy, strong, muscular, tall, small, just to name a few, and all the same: we are women and proud!"

Photos: The man who made Serena and Venus 'tough' Richard Williams has played a hugely influential role in the success of his daughters, U.S. tennis stars Serena and Venus. Hide Caption 1 of 13 Photos: The man who made Serena and Venus 'tough' Venus and Serena have won 28 grand slam singles titles between them and shared 13 grand slam doubles titles, both achieving the world No. 1 ranking. Hide Caption 2 of 13 Photos: The man who made Serena and Venus 'tough' From a young age, Venus and Serena were given tennis lessons in the city of Compton in Los Angeles County by their father, who was determined to produce two stars. Hide Caption 3 of 13 Photos: The man who made Serena and Venus 'tough' Richard is said to have been watching TV when he saw a Romanian tennis player win $40,000, before deciding to learn a sport he was unfamiliar with and teach his daughters to play. Hide Caption 4 of 13 Photos: The man who made Serena and Venus 'tough' Richard, seen here with Venus, devised a 78-page training regime for his daughters. Hide Caption 5 of 13 Photos: The man who made Serena and Venus 'tough' He made them keep journals about their tennis goals and how best to achieve them. Hide Caption 6 of 13 Photos: The man who made Serena and Venus 'tough' Richard, seen here with Venus during a practice session, instilled the motto purportedly first said by Benjamin Franklin: "If you fail to plan, you plan to fail." Hide Caption 7 of 13 Photos: The man who made Serena and Venus 'tough' In his autobiography, ''Black and White: The Way I See It,'' Richard describes how he brought ''busloads of kids from the local schools into Compton to surround the courts while Venus (pictured) and Serena practiced" to toughen them up. "I had the kids call them every curse word in the English language," he wrote. Hide Caption 8 of 13 Photos: The man who made Serena and Venus 'tough' Richard's work came to fruition in 1999, when Serena first won the U.S. Open, before Venus landed the following year's Wimbledon and U.S. Open titles. Here, Serena celebrates her maiden grand slam triumph. Hide Caption 9 of 13 Photos: The man who made Serena and Venus 'tough' Upon Venus' 2000 Wimbledon victory, Richard celebrated by shouting "Straight Outta Compton" (in reference to the song by controversial rap band N.W.A.) before then jumping up onto the commentary booth and embracing his daughter. Hide Caption 10 of 13 Photos: The man who made Serena and Venus 'tough' As Venus and Serena began to earn more success, Richard took a step back from their careers. Patrick Mouratoglou now coaches Serena, while Venus works with David Witt. Hide Caption 11 of 13 Photos: The man who made Serena and Venus 'tough' In 2002, Richard divorced from Oracene Price -- who also helped coach the young sisters -- having married in 1980. They are still often seated together during their daughters' matches. Hide Caption 12 of 13 Photos: The man who made Serena and Venus 'tough' In 2010, Richard married Lakeisha Graham, having met the previous year. Their son Dylan was born in 2012. Graham is 37 years younger than her husband, and one year older than Venus. Hide Caption 13 of 13

In describing her mom as "classy," Williams thanks Price for being the role model she needed to "endure all the hardships that I now regard as challenges" and talks of inheriting her mom's fortitue.

The letter ends with Williams writing: "Promise me, Mom, that you will continue to help. I'm not sure if I am as meek and strong as you are yet. I hope to get there one day. I love you dearly."

Before the birth of her daughter, Williams told Vogue she wanted to defend her Australian Open title in January 2018.

"It's the most outrageous plan," she told the fashion publication in August. "I just want to put that out there. That's, like, three months after I give birth. I'm not walking anything back, but I'm just saying it's pretty intense."