In coaching carousel era, Sofia Kenin and dad are as secure as it gets

"When I wasn't playing with Barbie dolls," says Sofia Kenin, "I was always playing with different kinds of balls, and my dad said, let's try tennis.

"As I started developing, as I started playing more tournaments and getting higher in the rankings, I saw I had massive potential."

For those who follow tennis closely, Kenin's potential isn't a trade secret. The 20-year-old has been playing in the main draw of the US Open since 2015, thanks to her success in the junior ranks, and she won her first WTA title earlier this year. But for those who watched Kenin play for the first time on Saturday, when she beat Serena Williams at Roland Garros in straight sets, her potential is likely a topic of discussion. How high can she climb?

Kenin, at least, believes she can go as high as possible.

"I've always wanted to be No. 1 in the world," says Kenin in her TenniStory, which you can watch above. (Run time: 3:09)

Perhaps Kenin made a few more believers after her confident performance on a worldwide stage. Against Williams, Kenin fired 23 winners and won 72 percent of her first-serve points; Serena, whose serve remains one of tennis' peerless strokes, won just 63 percent of such points, and was broken four times.

"I think she played really well," said Williams. "I feel like she, in that first set in particular, she hit pretty much inches from the line, and I haven't played anyone like that in a long time. So, like, yeah, she actually played really well."

There's certainly one other believer: Kenin's father, Alexander. The Kenins moved to the United States from Moscow; ever since, giving Sofia—who also goes by Sonya—the greatest chance to succeed in the game has been Alexander's goal.

Sofia has trained at some of the country's top tennis academies and was home-schooled, in order to prioritize her commitment to the sport, and her father has been by her side throughout her journey. With no formal training, Alexander has coached his daughter since she eschewed Barbie for a backhand, and he was on Court Philippe Chatrier on Saturday, beaming as Sofia completed the greatest win of her career.

"I knew I obviously wasn't the favorite," said Sofia. "I had my dad, my team, everyone there supporting me, and, you know, that's all I needed to win, and just happy to share this moment with them."