Long after the sun had disappeared below the stadium walls, after the faint of heart in the sellout crowd had gone home to dinner, Brian Gottfried completed his one-charge of the fading light brigade.

The last of the American men in the French Open tennis championships, Gottfried displayed grit and insatiable appetite for the net as he defeated Ilie Nastase, the champion of 1973 and No. 1 seed, 4-6, 3-6, 6-2, 6-2, 6-3, to reach the semifinals as darkness enveloped the windswept center court at Stade Roland Garros.

This was the first time Gottfried, 25, had ever beaten Nastase on a clay court and the first time he had ever come back from two sets down to win a match. Was it his most satisfying-victory.?"They all feel really good, anytime you can beat a player in the top five in the world, on his surface," Gottfried said after the three-hour, 20-minute epic that stirred spectators to rhythmic chopping and chanting.

"But to do it in a major championship, from two sets down . . . it hasn't really yet hit. Maybe I don't want it to hit for a few days more."

Gottfried's nex opponent will be Phil Dent, 27, the first Australian to make the semifinals since 1969. He also played a gutsy fifth set today, after blowing a two-seat, and eliminated Jose Higueras of Spain, 6-1, 6-3, 3-6, 6-7, 6-3.

Defending champion Adriano Panatta plays Raul Ramirez and Guillern Vilas opposes Wojtek Fibak in the other two men's quarterfinals Thursday.

Janet Newberry, the Italian Open champion, advanced to the women's semifinals by outlasting Kathy May, the U.S. clay-court champion and No. 2 seed, 6-4, 5-7, 6-2, in a tedious, error filled match. She next plays Florenta Mihai, who ousted Linky Boshoff, 6-3, 4-6, 7-5.

The Gottfried-Nastase match had a curious, even psychedelic pattern. Gottfried led, 3-0, with two breaks in the first set, lost 111 or the next 12 games, and then came back.

But after his long climb back, Gottfried had to serve two games for the match.

Nastase, whose magic had disappeared with the sunlight, revived long enough to save two match points after Gottfried got to 5-1, 40-15, on his serve in the fifth set, then broke with a backhand cross-court return that forced a lunging backhand volley error.

With the crowd howling for him to keep the match alive, Nastase held his own serve to 5-3 and won the first point of the ninth game, forcing another volley error with a soft forehand cross-court angle.

But Gottfried, serving with new balls, took a deep breath and decided that he would not let his grand resurrection go to waste. He won the last four points, sealing match with an angled backhand cross-court after Nastase had chipped his return of a second serve and come in.

In that final set, as he tried to close out the fading Nastase before darkness forced the matches' suspension, Gottfried was a commanding presence in the forecourt.

"I was really worried about the light. I wanted to swarm the net every chance I got - on his second serve, sometimes even on my second serve," he said. "I just wanted to take the net away from him, and he was trying to do the same thing."

Someone mentioned to Gottfried that he really looked as if he were flying when he ran eight straight games form 1-2 in the fourth set to 3-0 in the fifth, as if he felt he couldn't miss. Gottfried agreed in his style which is pleasant out taciturn and reserved even in jubilation.

He described in excruciating detail an important point on which a backhand down the line that he thought might stray wide was held in by the wind for winner. "I think somebody up there was catching the balls and keeping them in the court," he said.

Gottfried, who had not lost a set in four matches prior to today, started quickly, breaking Nastase in the first and third games. He then had two points for a 4-2 lead but, after saving six break points, double-faulted to lose his serve. He double-faulted gain to lose the set, and fell behind 0-5 in the second.

Through that portion of the match Gottfried looked almost punch-drunk, "like a pinball machine that has hit tilt," observed and observer in the pressbox.

Meanwhile, Nastase was playing superbly, controlling the ball in the wind as if he had every current charted. He displayed all his old genious, lobbing magnificently and playing with exquisite touch. He was the puppet master pulling at the strings around the court at his pleasure.

It made a fascinating contrast, Nastase's instinctive, free-flowing, improvisational game against Gottfried's textbook strokes and forth-right determination to get to the net.

Gottfried served and volleyed when he could, spun his serve in and approached on the first short ball when he had it.

When he was playing well, Nastase's returns were low and forced numerous volleying errors. But they started to come up again, and Gottfried became a terror at the net, slashingvolleys decisively, moving agilely and angling them for winnters.

The charge of the fading light brigade was on, and finally it conquered.