A bright future is being predicted for American star Cori Gauff. Still only 14, Gauff won the French Open junior title earlier this year at Roland Garros.
She beat fellow American Caty McNally in the final to claim her first junior grand slam title.
Last year Gauff became the youngest player ever to reach a US Open junior final when she finished runner-up.
"Overall, I want to be the best I can be and be the greatest," Gauff told CNN Sport last year after losing the US Open junior final to 16-year-old American Amanda Anisimova.
Gauff is subject to the sport's "age eligibility rule," which forms part of the player development program on the women's WTA Tour, limits the number of tournaments teenagers can play, to prevent early age burn-out.
The eligibility rule was introduced in 1995. Prior to that Jennifer Capriati, an American teen prodigy who turned pro at 13, reached the top 10 at 14 and became an Olympic champion at 16 at the 1992 Barcelona Games.
Capriati's career then went off the rails, though she staged a successful comeback in her mid-20s, clinching three majors in 2001 and 2002.
Russians Svetlana Kuznetsova, who won the 2004 US Open at the age of 19, and Maria Sharapova, who took the Wimbledon title that same year at 17, are the last teenagers to win a women's singles grand slam title.
Martina Hingis won all of her five Grand Slams before she'd turned 20.
Monica Seles won nine grand slams, her first coming in 1990 when as a 16-year-old she beat Steffi Graf.
Tracy Austin won the 1979 US Open when she beat Chris Evert in the final at the age of 16.
Spain's Arantxa Sanchez Vicario of Spain beat Graf (left) 7-6, 3-6, 7-5 in the French Open final when she was 17.