John McEnroe's court manners, if not his tennis, improved noticeably at the French Open today.

Nevertheless, he was the only American winner today as Tracy Austin was upset by Jo Durie; Kathy Horvath could not provide an encore to Saturday's victory over Martina Navratilova, losing to Mima Jausovec, and Jimmy Arias, the Italian Open champion, was unable to cope with the experience of clay-court specialist Guillermo Vilas.

McEnroe, seeded second, defeated Eliot Teltscher, 6-3, 3-6, 6-4, 6-1, on the slow red clay of Roland Garros Stadium. McEnroe will play defending champion Mats Wilander in the quarterfinals.

McEnroe was fined $3,350 earlier in the tournament for verbally abusing a linesman, kicking a photographer's camera and delaying play. He didn't dispute a single decision today and Teltscher helped McEnroe overcome his subpar form with key mistakes.

In other fourth-round men's matches, Vilas defeated Arias, 7-5, 6-3, 6-2; Wilander, the fifth seed, defeated Henrik Sundstrom, 6-4, 6-1, 6-3, and eighth-seeded Jose Higueras defeated No. 16 Andres Gomez, 7-6, 6-4, 7-6.

Other quarterfinal pairings are top-seeded Jimmy Connors against Christophe Roger-Vasselin; third-seeded Ivan Lendl against sixth-seeded Yannick Noah, and Higueras against Vilas.

In the two women's quarterfinals played today, Durie eliminated fourth-seeded Austin, 6-1, 4-6, 6-0; she already had beaten seeded players Kathy Rinaldi and Pam Shriver. Jausovec, the 1977 champion, had little trouble in a 6-1, 6-1 victory over Horvath, 17, who in her last match had handed Navratilova her first defeat since December.

Durie conceded only nine points in racing through the third set that Austin later described as "one of the worst of my career . . . She played well and I played pretty awful.

"I was not keeping the ball in play in the third set. I was making so many unforced errors, but I thought I would win the match after winning the second set."

Jausovec, unseeded despite her previous title, was in control against Horvath.

"It is hard to keep playing well after beating the No. 1 player in the world," Horvath said. "I had a great tournament. Part of the problem was that I was satisfied how I did and found it hard to do more."

In the other half of the women's draw, four-time champion Chris Evert Lloyd bids for a semifinal place against 1981 winner Hana Mandlikova. Third-seeded Andrea Jaeger plays Gretchen Rush, an amateur from Pittsburgh.

McEnroe trailed, 3-1, in the third set before winning five of the next six games. He had numerous bad strokes, failing to clear the net with drop shots and hitting shots far outside the line. But Teltscher started his downfall with a double fault that helped McEnroe reach 3-all in the third.

In the next game, McEnroe labored to find his form. Teltscher had two break points, but could not win.

"I think I am capable of playing better on clay than I did the last time I competed here two years ago," McEnroe said later. "But it has taken me a little longer than I expected to find my rhythm."

McEnroe conceded he must have a better start against Wilander.

"Against Wilander, it will be important to get off to a better start. I have never played against him on clay, but I don't think it is going to be a lot different than when we played before," said McEnroe, who has won both matches between the two.

"Obviously, Wilander is better on this court. I hope I am ready for a big match."

Wilander said he would make only a slight adjustment: "I am going to stay on the base line for the beginning, but will then come in a little more than I did today. You have to come in more when you play someone like McEnroe."