Just a few days before the start of Wimbledon, the record-shattering tennis star took to Instagram to share an inspirational flashback photo from her childhood.
"4 days until #Wimbledon," Williams wrote in the caption. "Would you believe me if I told you the girl on the left always dreamed of becoming the woman on the right? Keep fighting."
Williams posted the throwback -- showing her as a little girl playing tennis -- side-by-side with a photo of herself playing at a past Wimbledon tournament and looking every bit as fierce and powerful as a young athlete could ever hope to be.
It’s been a rocky road for Williams' as she's returned to the sport she loves after giving birth to her first child, baby girl Alexis Olympia, last September.
In May, the tennis champ and her sister, Venus Williams, won a doubles match during the French Open, just one day after Serena won her first grand slam match since taking a break from tennis during her pregnancy.
However, days later, the 36-year-old superstar had to withdraw from the French Open before she was to play a fourth-round match against Maria Sharapova, due to a chest muscle injury.
ET caught up with Serena back in March, where she revealed there's been a bit of mom guilt since returning to tennis.
"I've always wanted to be a mom but I never seemed to have time with my career," she said at the 14th Annual Desert Smash Celebrity Tennis Event in La Quinta, California. "I'm never a day without Olympia. She's my priority and every day I need to be home with her. I don't wanna miss any moments with her."