Jean Borotra, gaunt but sprightly, bounced into the room with youthful verve, still the "Bounding Basque" at age 79.

Always the most debonair of the "Four Musketeers," the fabled French tennis champions of the late 1920s and early 30s, he moved as nimbly as Fred Astaire, greeting everyone, stopping only to kiss a hand of all the ladies. This he does expertly, with the same practiced, flamboyant flourish with which he used to volley.

"A wonderful occasion," he said, mixing with the past winners of the French championships who returned this week to celebrate the 50th anniversary of Stade Roland Garros, a splendid tennis arena built in 1928 to host the first defense of the Davis Cup which "Les Mousquetaires" had seized in Philadelphia the previous year. "I only wish 'Toto' were here."

"Toto" was Jacques Brugnon, doubles player extraordinaire and an uncommonly nice man who imbued the Musketeers with exceptional elan. He died March 20, at the age of 82.

The other Musketeers - Borotra, Henri Cochet and Rene Lacoste - are still living relics of "the Golden Age of Sport." They joined with 33 other former singles champions, men and women, in the golden anniversary tribute to "the house les Mousquetaires built." And they will receive mementos from Jacques Chirac, the mayor of Paris, in center court ceremonies today.

Stade Roland Garros was erected by the city of Paris and named, as a civic memorial, for a French aviator who in 1918 flew off on a mission over the Mediterranean and never returned. Roland Garros had no connection with tennis, but he was honored here this week, too, his photo - revealing a dapper moustache and tweed cap - given a prominent place in anniversary displays.

But though named for a World War I hero, the tennis complex in Auteuil, on the western outskirts of Paris, is really a monument to the Musketeers whose most distinguished battlefield was its red clay center court. There they monopolized the Davis Cup until 1933, when Englishmen Fred Perry and Bunny Austin took it away.

The great enthusiasm for tennis that the Musketeers generated among their countrymen also helped build the French championships into one of the world's major tournaments. From its inception in 1881 until 1920 it was a "closed" affair, for Frenchmen only, but after going international it became the most important tournament on the continent.

Until 1975, when Forest Hills abandoned grass courts, the French was the only one of the traditional Grand Slam events played on clay. This year, with the U.S. Open shifting to cement, it regains that distinction.

"The French title should be as coveted as Wimbledon and the U.S. because, let's face it, it's the toughest to win," said Jack Kramer, who never played here and risked and reputation he earned in the 1940s as the world's best player on fast courts. "You have to work your tail off to win best-of-set matches on clay. This tournament is a real grind."

Tony Trabert, 47, won here in 1954-55, the last American male champion. "It didn't seem like that big a deal then, not as tough as everybody makes it out to be now," said the current U.S. Davis Cup captain, who was based in Paris in 1960-63 as European director of Kramer's pro tour, but hadn't been back since.

"You had to have the head and stomach to win on clay - concentration and gut it out," added Trabert, who had a fine time sightseeing and rediscovering old haunts with his daughter and son, who were born in Paris but left before they were old enough to explore it. "I wonder if today, with all the money in tennis in America, the guys are as willing to do that."

Ann Haydon Jones, the ladies' champion in 1961 and '66 recalled: "I first came here when I was 17, and at that stage I didn't really judge places on the beauty of their surroundings. It was important to win. I just wanted to get on Court 9 and practice hard enough to win one round in the French championships.

"It was a couple of years before I could appreciate the pleasure of Paris in the spring. My most striking memory of that first year was the toughness of playing here. You have to work so hard to win, and it's a struggle all the way - an endurance test.

"In those days we couldn't afford to stay at nice hotels, I didn't speak even enough French to order meals, and the organization was so lax that you'd call for a car and it would arrive two hours later. Mentally, too, it was a test. Even the seats in the stadium were an ordeal - solid concrete that numbed your bottom if you sat on them too long.

"But I was in the final here five times, I won twice, and it was my first major championship, so it will always have a special place in my heart."

This year's championship has produced few memorable matches, but the center court at Roland Garros remains one of the game's grand settings, especially on a sunny day, when a light breeze rustles the chestnut trees and evergreens that ring the old concrete amphitheater.

The stands are steeply banked giving the appearance of being peopled by many more than the 13,000 bodies who fill them day after day. The crowds, sporting colorful Parisian fashions, are knowledgeable and spirited but not as raucous as in other part of Europe.

Inflation has hit the championships, making a day at Roland Garros as expensive as other activities in Paris. A Coca-Cola cost $1.10, ice cream 90 cents, a hot dog a little more than $2. Even the pastries are costly, starting at more than a dollar, but the tarte aux fraises - flaky crust topped with fresh strawberries nestled on a layer of custard - is worth the price in any currency.