“I wish that the age rules were a little different, because they don’t have any limits on the men’s side,” she said. “But if it’s not going to change, I’ll take it. I see why they put the rules in place, to try not to burn out girls so young. But I feel as if I could do better things.”

Though no one doubts that the rule was well intentioned, many still question its fairness, including Gauff’s father, Corey.

“They put this thing in place for something in the past that didn’t go well,” he said. “That’s what the rule is for, and I don’t think that is this situation. I just want to give her the chance to compete with better players. You saw today — she’s playing a girl who plays a lot of WTA tournaments, and that’s not available to her.”

Gauff, who is from Florida, trains in France at Patrick Mouratoglou’s academy. Mouratoglou, who coaches Serena Williams, said some players might naturally peak earlier.

“I know it has been created in order to protect players, but I don’t think it protects players,” he said. “I think it only protects them from being as good as they can be. And I think Martina Hingis would never have been No. 1 in the world if there was this rule.”

In 1997, at age 16, Hingis won three Grand Slam singles titles, including the U.S. Open, where she beat the 17-year-old Venus Williams in the final. She won her last of five major singles titles at 18 in 1999.

“You can’t kill the momentum of the players,” Mouratoglou said. “Some players are playing their best tennis at 30, others at 16. Everybody is different, and you have to respect those differences.”