Hingis won her first three majors at the age of 16 in 1997, while at 16, Kournikova became second woman in Open Era to reach the Wimbledon semis in her Wimbledon debut
The WTA Age Eligibility Rules restricts the number of tournaments that players can enter, as well as the number of wild cards they receive between the ages of 14 and 17.
Fourteen-years olds can only participate in eight ITF (minor league tournaments), 15 year olds can play in 10 WTA level tournaments, 16 year olds can play in 12, and 17 year olds can play in 16.
“I think it's mainly because of the rules, that they have so many restrictions, which I don't always agree with,” Hingis said of the lack of teenagers at the top. “Everyone peaks at a different time. When you're younger, you learn faster. I think when you're like 18, at that time it's already harder to learn.”
Kournikova added, “You're starting to analyze more, starting to be afraid more. You're not as fearless. When you're younger, you just go out there and you don't think about the consequences and stuff like that. You're fearless.