Coco Gauff, the world's fourth-ranked player, admitted to struggling with impostor syndrome after defeating Belinda Bencic 6-3, 1-6, 6-3 to reach her first Miami Open semifinal.
At 22, she became the youngest American woman to advance to the semifinals in Miami since Serena Williams in 2004.
"I think sometimes I can get impostor syndrome," Gauff told reporters. "Even when they're saying my accomplishments, it doesn't feel like me. But tennis doesn't lie-the ball doesn't lie. I just have to believe in myself."
Her coach has been working to strengthen her self-belief amid persistent doubt.
"At moments, I believe in it. Other moments, I don't. I'm just trying to believe in it more," she said.
Gauff will face Czech star Karolina Muchova in the semifinals Thursday-having won all five of their previous meetings.