Photo: "You gave me the strength I didn't know I had" - Pregnant Serena Williams pens sweet message to her unborn child

Days after the Tennis star Serena Williams revealed that she is 20 weeks pregnant, she posted another photo showing her growing bump along with  touching message to her unborn baby. Read the message below...

My Dearest Baby, You gave me the strength I didn’t know I had. You taught me the true meaning of serenity and peace. I can't wait to meet you. I can't wait for you to join the players box next year. But most importantly, I am so happy to share being number one in the world with you.... once again today. On @alexisohanian bday. from the world's oldest number one to the world's youngest number one. -Your Mommy