It has been an unusual year for pain and suffering in tennis. John McEnroe and Tracy Austin, the defending U.S. Open champions, have had lamentable times in 1982, he with his ankle, she with her back. McEnroe, who won his first-round match today, defeating Tim Gullikson, 7-6 (7-2), 6-4, 7-5, has not won a tournament since the U.S. Indoors in Philadelphia in January.

Austin, who developed tendinitis in her right shoulder Thursday, has played only three tournaments in 1982 before this, largely because of a persistently bad back. The lack of play showed as she struggled to beat Beth Norton, 7-6 (7-4), 6-3.

Hana Mandlikova, the fifth seed, who missed 4 1/2 months this year because of a back injury, beat Susan Leo, 5-7, 6-3, 6-1. No. 7 Pam Shriver, of Lutherville, Md., who reinjured her shoulder two months ago at Wimbledon, beat Deborah Jevans, 6-0, 6-1.

Chris Evert Lloyd beat Kelly Henry, 6-1, 6-0. "She didn't push me at all," Evert said, except to make her get up at 8 a.m. for the first match of the day.

The final night match, between third-seeded Ivan Lendl and Tim Mayotte, was suspended because of rain with Lendl having won the first set, 6-4, and trailing in the second set, 1-2.

Evert believes that many of the injuries to the younger players, like Austin and Andrea Jaeger, come from doing too much too soon, playing too many tournaments, a suggestion they adamantly reject.

"I think it shows they are playing too much at a young age, when their bodies and bones are still forming," Evert said. "I feel so fortunate that I came along when I did. I paced myself a lot more. Tennis has changed. They feel the pressure to play every week to keep up their rankings."

There is also more pressure from tougher matches early in a tournament, Evert said. So Austin was reminded tonight. In the first set there were six service breaks, with Norton breaking in the fourth and sixth games to take a 4-2 lead as she kept Austin moving around the court with penetrating ground strokes.

In the seventh game, Norton missed an opportunity to take a 5-2 lead when Austin hit a forehand down the line that she could not return. Austin broke Norton on two unforced errors to close within a game, 4-3.

But in the next game Austin made three unforced errors and Norton, the 71st ranked player, broke back. Norton served for the set but made three unforced errors again. It went to a tie breaker. Again, Norton took the initiative, going up 2-0, and then 3-1. But she double faulted to make it 3-2 and another backhand unforced error tied it at 3. (She had 28 backhand and 33 forehand errors.) She took the lead with a forehand winner down the line. But Austin retaliated with a backhand cross court winner that hit the line and it was 4-all. Norton made three more unforced errors to give Austin the set.

In the second set, Austin had to come from behind again, after Norton broke to go up, 2-1. Austin won the next four games and ultimately the match.

Part of the struggle, Austin said, was lack of match play. "But I don't want to say that because I want to give her credit," she said.

Evert believes Austin has changed as a result of her injuries. "She used to be a little more nervous and uptight," Evert said. "She's calmer, nicer now."

McEnroe's injuries have had an effect, too, a palpable loss of confidence that he has struggled all spring to regain. McEnroe sprained his left ankle in Brussels in March, just as he felt he was finally about to get going. Because he wasn't moving well, he became tentative, he says.

In the match against Gullikson, which began Wednesday night and was postponed because of a power failure, McEnroe said he was still "accepting losing points . . . There were balls I should have been all over. Instead I watched it float by."

But in the first-set tie breaker, McEnroe (who got in 53 percent of his first serves) led, 4-1, on two serves that Gullikson could not handle and returned long. A wide McEnroe backhand made it 4-2, but that proved to be Gullikson's last point. McEnroe finished off the set with one of the six aces he had in the match. In the second set, with the score tied at 2, Gullikson double faulted (he had four in the match) to give McEnroe a break point. He saved that break point but double faulted again and McEnroe had the break, the only one of the set.

Gullikson, who beat McEnroe at Wimbledon in 1979, took a 3-0 lead in the third set, breaking in the second game, as McEnroe allowed a ball to float by him, thinking it was long. It was good. But McEnroe broke back in the fifth game and held in the sixth (winning the last point on an ace) and broke again in the seventh. McEnroe served for the match at 5-4 and let the opportunity slip by, with a long, sloppy backhand. It was 5-all.

Gullikson fell behind 0-30 on his serve but won the next three points and had a game point. A wide backhand made it deuce, the first of four. McEnroe hit a low sharp return at Gullikson's feet to give him his fourth break point. This time, he made the most of it. A forehand passing shot gave him the break and he served out the set.

His confidence, he said, "isn't the hottest it's ever been," not as hot as a man who has won three consecutive Opens would like. "I had a tough stage and I think you go through periods and you don't know when you come out of it," he said. "I still believe in myself and I will always believe in myself. Sometimes when things start going wrong you get aggravated at everything and it's important not to do that."