Coco Gauff during Day 6 of the 2019 US Open. (Getty Images)

Coco Gauff is not just changing how fans view teenagers on tour, but also the general acceptance of the WTA Rulebook. Since the 15-year-old made it to the round of 16 at Wimbledon, people began to question whether the WTA age restriction rule should apply to her, or any young teenager. 

Under the rule, teenagers under 18 are restricted to a certain number of professional tournaments a year. A 15-year-old is allowed to play 10 WTA events per year, with an additional four added on depending on performance. Gauff has played nine events since turning 15 in March, which means she can player another five before her 16th birthday on March 13, 2020.

The rules were created in the mid-1990s—largely due to Jennifer Capriati—to prevent injury and burn out in young women. Roger Federer is not a big supporter of the age rule. 

"I understand the rule completely that they want the young players not to play too much. I've told the WTA they should loosen up the rules," he said. "Maybe your best time, and your best time is from 14 to 20 for some reason. It's not like for everybody else from 20 to 30. So in a way you take away that opportunity."