She is one of the greatest tennis players of all time, but even when Serena Williams is on the court her mind is elsewhere: mainly on her daughter, Olympia.

The 37-year-old recently sat-down with Forbes and talked about just how much she misses her little one, 1, while she’s away competing. “I actually prefer playing in the day because I get to go home and see my baby,” the star athlete — who is currently competing at the U.S. Open — revealed. “I’ve been missing her the last few nights when I play.”

The tennis legend shares her only child with her husband, Alexis Ohanian. The pair tied the knot in 2017. “In the beginning she would really be upset when I left,” Serena continued. “And now she’s a little bit better. I think I’m a little more upset. But at the same time, she definitely still takes it a little hard. She’s still super young.” However, the Grand Slam winner finds it difficult to spend time away from her girl.

“You know, it’s hard. Sometimes my heart literally aches when I’m not around her. But, you know, it’s good for me, I guess, to keep working and just — to all moms out there that it’s not easy,” Serena told the outlet. “It’s really kind of painful sometimes. Sometimes you just have to do what you have to do.”

Serena goes on to explain the logistics of tennis tournaments and how they get in the way of her time with her child. “Usually I’m with her, I can train really early in the morning and be done pretty early with my day, and I can just stay with her for the rest of the day,” she said.

“In tournament schedule, it’s totally different, so I’m kind of pushed out of my usual day-to-day life,” Serena added. “Oh, my God, I’m not with her. That’s been the most, I mean, the toughest thing I have ever dealt with in my career.” Spending time with Olympia is everything to Serena and Alexis, and the cofounder of Reddit recently opened up about taking paternity leave when his daughter was born.

Taking leave set me off on the right foot for sharing parental responsibilities,” Alexis told The New York Times. “Two years later, there is no stigma in our house about me changing diapers, feeding Olympia, doing her hair or anything else I might need to do in a pinch.” So incredible!