What inspired Serena Williams’ famous on-court grunt?

If you’ve ever watched Serena Williams in action on the tennis court, you’ve probably wondered what’s behind the sounds she makes when she hits the ball. You know, those powerful grunts that can only come from a fierce player like Williams—whose average serve hits 105 mph, by the way—and that make you feel really sorry for the tennis ball at the other end of her swing. Listen to them for yourself here:

Now, the star is sharing the story behind her on-field battle cry. On a July 4 episode of “Hot Ones,” Williams told host Sean Evans that she started growling in honor of one of her favorite players, Monica Seleswho was ranked number one in the world in 1991 and considered one of the most grumpy OGs on the field.

“I growl because when I was little, I loved this tennis player named Monica Seles and she growls. She had this really cool growl. And I loved it, I was like, ‘This is so cool,’” she said, testing her taste buds with a sample of really spicy chicken wings. “So I literally growl at her and then it just became natural and then my growl became like a… It was really loud.”

But now, after nearly 30 years on the professional tennis circuit, Williams says the growl has become second nature and sometimes comes out when she’s not playing tennis.

“I guess it’s a form of breathing,” she said. “I grunt while I play golf now. It’s like it’s part of my life.”

During her conversation with Evans, Williams also discussed her face-off with older sister Venus at the 2003 Australian Open – a match Serena called one of the most intense between the two.

Williams said the pressure was high because it was her first opportunity to win four Grand Slam titles in a row – a feat now known as the ‘Serena Slam’.

“It was a tough match because she actually played really well. And to be honest, she should have won. And I remember she missed a shot that she wouldn’t have missed in any other match,” she said. “And I could see that something had gone wrong… even for a split second… It was tough.”

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