John McEnroe's triumphant Wimbledon fortnight was back in the news today, but not in a manner that pleased the world's top-ranked player.

This afternoon, hours before McEnroe destroyed Tom Gullikson, 6-3, 6-1, 6-3, in the second round of the U.S. Open tennis championships at the National Tennis Center, the Men's International Professional Tennis Council announced that it will fine McEnroe $5,000 as a result of his behavior during Wimbledon.

The $5,000 fine -- which McEnroe can appeal to a three-man arbitration board -- is for aggravated behavior, a major offense under the council's code of conduct. McEnroe also was fined $750 three times for minor offenses during Wimbledon and has paid two of those fines. The third he appealed and the appeal was denied by M. Marshall Happer III, the council's administrator.

"I'm never surprised by anything the council does," McEnroe said after his match tonight. "I don't think it was fair. It's unfair to do something like this in the middle of a tournament.

"There are some fines I've gotten in the past which I've deserved but I don't think this fine was fair. Under the rule of aggravated behavior what I did I should not have been fined anything for.

"I think the umpires are out to prove something now. They want to prove they can handle the big man or the guy who's caused problems in the past. That's not to say I haven't done things in the past that were wrong but the umpires are looking for me. I think that's obvious."

The McEnroe fine overshadowed all the on-court events during the third day of the tournament. While McEnroe was advancing easily, third-seeded Ivan Lendl had a few nervous moments in beating Jeff Borowiak, an American with a penchant for upsets, 7-6, 6-1, 7-6.

No. 13 seed Yannick Noah had more than a few anxious moments. In fact, he thought at one point he was going to lose to recent college graduate Andy Andrews, ranked No. 436 in the world. Noah finally escaped with a scintillating 6-3, 6-4, 6-7, 4-6, 6-2 victory after three hours 21 minutes on the grandstand court.

But No. 10 seed Brian Teacher was not as lucky. He was beaten by Marty Davis, 22, who made the University of California tennis team as a walk-on. A pro for less than a year, Davis showed tremendous quickness in shocking Teacher, this year's Australian Open champion, 2-6, 7-6, 6-2, 6-4.

Another loser early in the day was Stan Smith, the 1971 champion, who had won a courageous five-set duel with John Sadri two days ago. Today, Smith could not handle the spinning passing shots of Ramesh Krishnan, who advanced, 6-4, 6-3, 6-3.

But the talk today was not of upsets, close matches or great tennis. McEnroe was on center stage even when he wasn't present. The $5,000 figure was seen by many as a slap in the face to the hallowed Wimbledon Tournament Committee, which had written the council a letter recommending a $10,000 fine, the maximum dollar figure allowable under the code of conduct.

"The fact is what was involved here was verbal abuse, not physical abuse," said Happer, who recommended the fine to the nine-man council which upheld his recommendation. "There are a lot of things worse than verbal abuse. I did not think that the maximum fine was warranted."

Happer's announcement caused an uproar among members of the British press who were outraged by the decision to halve the recommendation of the Wimbledon committee. One British writer stood up and asked, in shocked tones, "How can the fine be so small after an incident generally considered the worst of the decade?"

Ironically, it was in a first-round match against Gullikson at Wimbledon that McEnroe had his most serious problems. Tonight, on a brisk evening, McEnroe was on his best behavior, helped by the fact that Gullikson barely put up a fight.

The only incidents came early and late in the 85-minute match. Serving at 2-2, 15-all in the first set, McEnroe thought a Gullikson backhand was wide. The line judge and umpire thought different. McEnroe stalked around briefly then took a ball and placed it in the doubles alley where he thought it had landed.

The crowd hooted, then cheered when McEnroe lost the next point to go down 15-40. But he came back with two booming serves to avoid the break and for most of the match it was Gullikson who quibbled with the officials. At the end of that very same game, Gullikson took a ball and placed it where he thought a McEnroe serve had landed out.

It would have ended without further incident except that McEnroe let a couple of noisy fans, who yelled out while he was serving for the match, get to him. Frustrated, he yelled, "Shut up, just shut up while I'm in the middle of my serve!"

He was subjected to several more catcalls before he ended the match with a gorgeous first serve.

Although he steered questions away from the fine, it, along with the reaction of the crowd in his hometown, clearly bothered McEnroe.

"The crowd's waiting for me to do something," he said. "The minute I even sniff at a call they get going. I don't need that here. It's disappointing, very frustrating but I know I'm going to have to live with it for a while, maybe six months, maybe longer. I can't avoid it. It may be time to do some serious thinking."

What kind of serious thinking, he was asked.

"I don't know, I'll have to think about it."

The questioning of McEnroe was almost tame compared to the 45-minute grilling Happer was subjected to after announcing the fine. The British press was uniformly outraged that the fine was not larger. Many in the American press were upset it was so large, some noting that Eliot Teltscher, another American, was fined just $2,500 for pushing an umpire after losing at the French Open.

"There were extenuating circumstances there," Happer said when asked to explain. He also added that the council is rewriting its code of conduct for 1982 to make the penalties for misbehavior stiffer.