PARIS—World No. 1 Serena Williams says she is quite pleased to see that the United States has 15 women in the Roland Garros draw, the most of any country.

“I think the quality over the past year has jumped tremendously with the female U.S. players,” she said. “I think last year here, outside of me, all the U.S. girls did really, really well, and I think we started to see then just so many players just popping up left and right. Fifteen in the main draw? That’s pretty awesome. So it is a lot of players, but they’re all really young. So there is still an opportunity to grow.”