The GOAT, Serena Williams, covers the September issue of Vogue and is discussing her pending retirement from playing tennis professionally.

Williams opens up about her decision, citing how she feels she has to choose between family and her career.

Williams said she was in the car with her daughter, Olympia, who was using Williams’ phone. An app asked Olympia what she wanted to be growing up and Williams said she heard her daughter say “a big sister.”

“I never wanted to have to choose between tennis and a family,” Williams wrote in the reflection piece for Vogue. “I don’t think it’s fair. If I were a guy, I wouldn’t be writing this because I’d be out there playing and winning while my wife was doing the physical labor of expanding our family. Maybe I’d be more of a Tom Brady if I had that opportunity.”

Williams said she loved being pregnant and loves being a woman, but acknowledges the hard decision of leaving tennis.

“I have never liked the word retirement,” Williams said. “It doesn’t feel like a modern word to me. I’ve been thinking of this as a transition, but I want to be sensitive about how I use that word, which means something very specific and important to a community of people. Maybe the best word to describe what I’m up to is evolution.”

Williams said there is “no happiness” in choosing to leave tennis, calling it “the hardest thing that I could ever imagine.”

“I hate it. I hate that I have to be at this crossroads,” Williams said regarding family and playing a sport she has played her entire life. “The fact is that nothing is a sacrifice for me when it comes to Olympia.”

Williams plans to leave tennis after playing in the next U.S. Open.