According to ESPN:
When Victoria Duval was 7 years old, she trailed along once again to watch her older brothers play in a tennis tournament in Santo Domingo, near her childhood home in Haiti. The tournament director had always watched her sitting on her mother Nadine’s lap and suggested she let Victoria compete this time, if only so Nadine could focus on the matches.
Duval didn’t know where to stand on the court, how to hold the racquet and certainly not how to keep score, but you’ve probably already figured out that the plucky little girl won the whole tournament. At that moment, tennis forever trumped her previous love of ballet.
“After that, my mom was like, ‘OK, you have to choose now,'” Duval said. “Tennis seemed to be appropriate.”