Tennis Was Once Ruled by Teenagers. Now, Not So Much.

Wherever 18-year-old João Fonseca goes, he hears his name chanted as if he were akin to his countrymen, the Brazilian soccer stars Ronaldo, Pelé and Neymar. Mirra Andreeva, also 18, gets interview requests while she waits in line at a pharmacy in New York City.

Teenage tennis prodigies used to be as common as gut tennis strings. Chris Evert was 16 when she reached her first U.S. Open semifinal in 1971. Steffi Graf was 17 when she captured the first of her six French championships. Monica Seles, Arantxa Sánchez Vicario, Martina Hingis and Maria Sharapova were all under 20 when they catapulted to fame.

Bjorn Borg was 18 when he won the first of his six French Open titles in 1974. Boris Becker was 17 when he grabbed his first Wimbledon. Stefan Edberg, Pete Sampras, Michael Chang and Rafael Nadal were all teenagers when they won their first majors.

Over the years, as the sport became more physical and endurance minded, necessitating more mature bodies, the tide changed. Equipment, fitness and nutritional advances have also allowed players to continue competing into their mid-30s. Forty-year-old Stan Wawrinka, for example, a three-time major winner, is playing in his 20th French Open, which begins on Sunday.

There is only one teenage man, Jakub Mensik, 19, of the Czech Republic, ranked in the ATP’s top 60 and only one teenage woman, the Russian Andreeva, who is ranked a career-high No. 6, in the WTA’s top 60. Fonseca is No. 65.