Andrei Chesnokov doesn't know when he will play in a major tennis tournament again. He doesn't know if he will play at Wimbledon this year -- or ever. He doesn't know if he will play in the U.S. Open or in the French Open again next year.

The reason for his uncertainty: The Soviet Union's national committee of sports, which tells him when and where and if he will play, hasn't told him anything. Today, though, Chesnokov carved a memory for himself with a stunning 5-7, 7-5, 6-3, 6-3 second-round upset of Eliot Teltscher, the eighth seed in the French Open.

The irony of a Soviet beating an American on the clay of Roland Garros while being cheered on by several thousand French fans seemed to be lost on Chesnokov, who is 19, with blond hair, blue eyes and a whippy, two-handed backhand.

"I just wanted to play well," he said through an interpreter. "At first I didn't think I could beat him, but midway in the first set I found I could do it. It gave me a lot of confidence."

Chesnokov's out-of-nowhere victory was the highlight of a chilly, windy day on which the men produced most of the drama. As Chesnokov, who had to play three qualifying matches to reach the main draw, was beating Teltscher, 10th-seeded Aaron Krickstein was outlasting 1977 champion Guillermo Vilas over three hours, 6-4, 3-6, 6-1, 6-3.

Meanwhile, No. 2 seed Ivan Lendl survived a set point and a tie breaker in the first set and went on to beat Jan Gunnarson, 7-6 (7-4) 6-3, 6-2, and No. 6 Anders Jarryd, No. 7 Joakim Nystrom and No. 11 Miloslav Mecir all were winning.

The only women's seed to fall was No. 13 Kathy Rinaldi, a 6-4, 6-2 loser to Raffaela Reggi. Rinaldi may have known what she was doing, though, since Reggi has the dubious honor of playing defending champion Martina Navratilova in the fourth round.

Today, Navratilova defeated Catherine Tanvier, 6-0, 6-0. Tanvier is a good player, but against Navratilova she was helpless. In three matches, Navratilova has lost four games and four of her six sets have been won at love. Her postmatch news conferences, for lack of anything else to talk about, have deteriorated into discussions about her four-pound fox terrier "KD," which is short for Killer Dog.

Chesnokov's news conference lasted almost as long as his match, simply because almost no one here had heard of him before this week. He is the fifth-ranked player in the Soviet Union and is the first male from his country to play here in 10 years.

Teltscher learned about Chesnokov quickly today. Like Teltscher, Chesnokov plays the base line, but he is quick and got to a lot of balls that looked like winners. The match turned in the second set when Teltscher double-faulted at set point.

"Winning the set gave me confidence," Chesnokov said. "I felt like he thought I was a little ahead of his game and that surprised him."

Teltscher's game deteriorated rapidly after the second set. Chesnokov quickly broke in the third and his domination grew with each game. When Chesnokov broke again to start the fourth set, it was apparent Teltscher would become yet another U.S. man to fall early in this tournament.

Krickstein avoided that fate by playing the best match of the week against Vilas. "It was like Custer's last stand," Krickstein's coach, Nick Bollettieri, said. "That may have been Vilas' last great match."

Vilas, 32, has dropped to 59th in the rankings, has been deserted by his long-time coach, Ion Tiriac, and has lost to players in recent months he would have toyed with several years ago.

But today, playing near dusk on a windy court No. 1, Vilas looked almost like the man who dominated tennis in 1977. He ran down every ball, made several impossible shots and appeared willing to stay on the court all night if necessary.

"I played very well today," Vilas said. "It's the best in a long time. If he hadn't played so well, I would have won. If I had been able to get it to a fifth set, I think I would have won."

Krickstein, 18, showed great poise when faced with Vilas' superb play. Although he kept muttering to himself as Vilas hit winners, Krickstein kept calm. He was cool enough to glance at the scoreboard during the 68-minute first set and say with a shrug, "Six games in 50 minutes. We're moving right along."

If Krickstein had not gotten his whipsaw forehand going in the last two sets, the two would have moved right along until dark. But he did get the forehand working -- Krickstein will hit a backhand only in a life-threatening situation -- and it was just too strong for Vilas.

"If he can play like that all the time, he can win the tournament," Vilas said. "But I don't think he's that consistent yet. He plays a high-risk game."

Lendl, the defending men's champion, took several risks in the first set of his match. He seemed to be playing in a semitrance until Gunnarson broke him to lead, 5-3. At that moment, Lendl seemed to look around and note he was at center court at Roland Garros, not on a practice court at home in Greenwich, Conn.

As if by magic, Lendl's forehand arrived, the big serve showed up and Gunnarson soon was gone. His one chance came in the tie breaker but he pushed a backhand wide at 4-all, then barely touched two serves from his opponent. Lendl never was in trouble again.