Guillermo Vilas, determined to erase the label of "The Eternal Second" pinned on him by the press in his native Argentina, won the French open tennis championship, his first grand slam title, by routing Brian Gottfried, 6-0, 6-3, 6-0, today.

Vilas' triumph on a gray, gloomy, occasionally rainy day that made the red clay of Stade Roland Garros play even slower than usual, was the most decisive in a men's singles final since the French became an international championship in 1925.

It was even more lopsided than Vilas' 6-2, 6-0, 6-4 victory over Gottfried in the opening match of Argentina's 3-2 victory over the U.S. in the Davis Cup American Zone final at Buenos Aires five weeks ago.

Gottfried seemed more numbed by Vilas' relentless torrent of topspin passing shots than disappointed in his failure to become the first U.S. men's singles champ here since Tony Trabert won in 1955.

Vilas, 24, won only nine games in his previous appearance in the final here, losing to Bjorn Borg, 6-2, 6-3, 6-4, in 1975.

Runner-up in the 1976 World Championship of Tennis finals and Italian Open and this year's Australian Open as well, he was increasingly haunted by voices whisphering that he couldn't win the big ones.

Gottfried, 25, has won four of 11 career meetings with vilas, two of four this year, but has been completely overwhelmed in the two matches on red clay. Today's heavy conditions favored Vilas, who watched the aggressive Gottfried bore into the net repeatedly and simply used him for target practice.

Gottfried hit the kind of volleys that would be winners on grass or hard surface courts, but not on clay where the ball does not shoot through or die.

On this surface, against a player of Vilas' strength and quickness, the volley must be much more sharply angled. The only way to put it away is to hit it out of reach.

Gottfried didn't do this and so Vilas was running down practically everything, firing passing shots back in barrages. Eventually, on the second or third or fourth try, he whistled one cleanly past Gottfried's lunge or forced a volleying error.

Gottfried knew that he could not outduel VIlas from the backcourt, a notion that was reinforced early, so he tried to attack the net as often as possible. He went in behind first services, chipped returns of Vilas's second serve, any short ball or reasonably deep approach.

Initially he was volleying agilely, sometimes acrobatically, but Vilas' passing shots were just too formidable. Gottfried wanted to be solid as a rockpile at the net, but Vilas knocked the would-be stone wall down.

He hammered so often and so potently that eventually Gottfried crumbled.

The placid Floridian played progressively worse. He started raking approach shots into the net and grew overanxious on his returns. His ground storkes and volleying became increasingly shaky.

By the ned, Gottfried was playing as miserably as Vilas was well. From 40-15 in the last game he blew two easy forehand volleys, and after getting an advantage point he embarrassingly mishit forehand volley and backhand half-volley that ricocheted wildly off his racket like pop fouls.

Then he hit a backhand volley wide to end what had become for him a 1 hour 58-minute ordeal. In all, he lost eight of the 11 games he served and had only five break points against Vilas, never breaking him.

"When he hits that many passing shots, it gets to your mind a litte bit," said Gottfried, who has won four tournmanets and lost five finals this year. "Those mistakes at the end were mostly mental. He just completely wore me down."

Vilas, always a better front-runner than come-from-behind player, gathered momentum and purpose as he neared fulfillment of his driving ambition to win one of the major titles.

He was crouching forward hungrily on his service returns, swaying from side to side like a panther eager to pounce. Occasionally he tapped the clay with his racket, in a little ritual of readiness.

Between points he danced like a prizefighter in his corner, keeping his sturdy legs limber, his muscular body warm in the chilly, breezy clamminess that had the sellout crowd of 14,000 shivering.

Light rain fell through most of the first set, stopped, then started again three games from the end. Rain gear rustled and umbrellas clicked open as spectators bundled up, but Vilas, whose concentration is often bothered by such distractions, was plugged in and all business.

He won the first point with a back-hand down the line pass and broke at 30 in that game, Gottfried netting a forehand volley off a backhand crosscourt after saving himself with two stretching volleys off similar passing attempts. That all foreshadowed what was to come later.

Vilas did not have a break point against him in the set and broke Gottfried again at 15 in the third game and t 30 in the fifth. The topspin backhand down-the-line passes he hit from 30-30 in that fifth game should be preserved as lessons in the execution of that stroke.

Vilas' only hesitant moments came at the start of the second set. In the first game the grip on one of his rackets came loose and he took it over to his coach-manager-Svengali, the hulking, Hirsute Rumanian Davis Cupper Ion Tiriac, who sat glowering and puffing a cigarette in a courtisde box. Tiriac put on a new grip, and Vilas resumed using the racket a few games later.

Gottfried held serve twice to 2-1, the second time from 0-30, and had his first three break points in the fourt game. But he made errors on all three, netting a backhand return badly on the last, and Vilas was out of trouble.

Vilas broke in the next game and rolled thereafter. The only further two break points against him were in the third game of the third set.

Just before the last game, a cluster of balloons - red, green, blue and orange - rose from the stands and floated away into the gray sky. Gottfried might as well have been going with them.

At the end, Vilas - swarmed by children who had rushed onto the court - ran over and embraced Tiriac, then raised his arm to the crowd triumphantly. Then he received his trophy and first prize money of $38,000 (Gottfried got $19,000).