Coco Gauff ended her 2019 season on Saturday by winning the doubles title at the Luxembourg Open with Caty McNally . It was a triumphant finish to a year in which the 15-year-old Gauff broke onto the tennis scene with exhilarating runs at Wimbledon and the United States Open.

Last week she won her first WTA singles title and reached No. 71 in the rankings after being No. 453 on her 15th birthday on March 13.

She did it all within the confines of the WTA’s age eligibility rule, which limits the number of tournaments girls under 18 can play.

Many American teenagers look forward to their 16th birthdays because of the resulting increase in driving privileges. When Gauff turns 16 in March, she will gain a different sort of freedom: an increase in the number of tournaments she can play, to 16 from 14 .