New mum Serena Williams has opened up to her mother in a touching letter online.

The tennis ace gave birth to a little girl, Alexis Olympia, at the start of the month and like lots of new mamas, she's speaking out about her respect for her own mum.

A post shared by Serena Williams (@serenawilliams) on Sep 13, 2017 at 6:39am PDT

In a letter shared on Reddit, the website co-founded by Williams' partner Alexis Ohanian, Williams admits that she doesn't know how her mum Oracene coped with the negative attention Serena has endured throughout her career. "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. "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."

A post shared by Serena Williams (@serenawilliams) on Jul 12, 2016 at 4:14am PDT

She also praised her mum's "class", writing, "I only wish I could take your lead. I am trying, though, and God is not done with me yet. I have a LONG way to go, but thank you." "Thank you for being the role model I needed to endure all the hardships that I now regard as a challenges--ones that I enjoy. "I hope to teach my baby Alexis Olympia the same, and have the same fortitude you have had." The letter in full, which you can read below, is something a lot of mums will relate to - there's nothing like being a parent for the first time to make you realise just how strong our own mothers are.  

Dear Mom, You are one of the strongest women I know. I was looking at my daughter (OMG, yes, I have a daughter ?) and she has my arms and legs! My exact same strong, muscular, powerful, sensational arms and body. 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! You are so classy, I only wish I could take your lead. I am trying, though, and God is not done with me yet. I have a LONG way to go, but thank you. Thank you for being the role model I needed to endure all the hardships that I now regard as a challenges--ones that I enjoy. I hope to teach my baby Alexis Olympia the same, and have the same fortitude you have had. 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. Your youngest of five, Serena