While several teenagers display their talent in the French Open, an older woman reminds them veterans cannot be forgotten.

Eight women with an average age of 18 Thursday advanced to the fourth round of the $3.9 million tournament, including top-seeded Steffi Graf of West Germany and fourth-seeded Gabriela Sabatini of Argentina.One of the veterans of women's tennis, 31-year-old Martina Navratilova, was to take center court today to defend the honor of an earlier generation. Navratilova's longtime rival and friend, fellow American Chris Evert, had her match postponed until Saturday to give her time to recover from a bone scan on her bruised heel.

Second-seeded Navratilova, who has been in the finals at Roland Garros stadium each of the past four years, was slated to face Austrian Barbara Paulus. Third-seeded Evert, 33, a seven-time French Open champion, was granted a delay in her third-round match against 16-year-old Spaniard Arantxa Sanchez after taking the bone scan, which showed no fracture of the sore heel.

The key men's matches today included a third-round encounter between second-seeded Stefan Edberg of Sweden and compatriot Jan Gunnarsson, and a meeting between third-seeded Swede Mats Wilander and Slobodan Zivojinovic of Yugoslavia.

Other matches involving seeded men set for today included sixth-seeded Yannick Noah of France against Jakob Hlasek of Switzerland, and ninth-seeded American Andre Agassi playing Anders Vysand of the Soviet Union, ranked 256th in the world.

Young women dominated Thursday, with 18-year-olds Graf and Sabatini setting the pace. Graf, the defending champion on the soft red clay of Roland Garros, rolled past American Susan Sloane 6-0, 6-1, and has relinquished only six games in her first three matches. Sabatini had little trouble with Masako Yanagi 6-2, 6-1.

In the biggest upset so far in the tournament, 16-year-old Conchita Martinez of Spain - ranked 279th in the world and played in her first major professional tournament just last week - shocked ninth-seeded American Lori McNeil 1-6, 6-3, 6-1.

Another young winner was 15-year-old Brenda Schultz of Holland, who ousted 14th-seeded Sandra Cecchini of Italy 6-4, 7-5.