It was on the sixth point of the third set tie breaker in the epic U.S. Open championship match today that John McEnroe eloquently summed up just how he feels about his rivalry with Bjorn Borg.

Appropriately, the occasion for his summation was an outburst, an instinctive thought in a moment of anger when he believed he had been victimized by a bad call.

As he and Borg changed sides of the the court with the tie breaker game even, 3-3, McEnroe pointed his finger at chair umpire Ken Slye and said: "You just made the worst call I've seen in the biggest match of all time."

This was not the biggest match of all time. But for Borg it was as big as any he has ever played because it would have been a giant step toward the Grand Slam he covets. And, by winning, he would have removed the one blemish on his astonishing record -- no U.S. Open championship.

For McEnroe, this was his chance to even the 1980 score. He has lost a magnificent five-set Wimbledon final to Borg and has not played him since. "I figured if I was ever going to beat him this was the place to do it," McEnroe said. "This is my best surface (rubberized asphalt) and it's probably his worst. If I didn't beat him here I don't know when I would have beaten him."

Which is why today's 7-6, 6-1, 6-7, 6-4 win was so important to McEnroe. At age 21, he has clearly established himself as the world's No. 2 player. But if he is to catch up to Borg he must beat him. Another loss would have been a blow, not just because he wanted to defend the title he won here last year but because he he might have developed a Borg fixation,a belief that he could not beat the Swede had he lost after winning the first two sets today.

"There were times out there where I started to think I was never going to beat the guy," McEnroe admitted. "at the end of the fourth set, I thought Iwas in trouble. I was really tired and I know he just gets stronger as a match goes on. Right then I felt like my body was going to fall off."

There was no change of sides after Borg won the fourth set but the crowd was cheering so wildly that McEnroe had a moment to walk off the court, grab a sip of water and try to regroup his thoughts.

"I went over there for two reasons, "he said. "First, I was thirsty. Second, I wanted to take a minute to get my head back together. I had to start pushing again, I knew that."

Few would have blamed McEnroe if he had lost the fifth set. He had played 4 hours 16 minutes Saturday to beat Jimmy Connors and had already played 3 hours 30 minutes through four sets today.

Even McEnroe conceded that losing the fifth set would not have shocked him. "I figured I had nothing to lose," he said. "If I had lost, I would have just been another victim of his."

While most of the 20,172 in the stadium thought they were about to witness Borg's 14th straight win in a five-set match, at least one person thought McEnroe would survive.

"He was exhausted, I could tell by the way he was moving," said McEnroe's doubles partner, Peter Fleming. "ButJunior's very tough mentally. You can be exhausted physicallly and hang in if you're strong mentally. He had been there before, he had played singles and doubles for four or five hours the day before a final and been okay. I knew he could do it if he hung tough."

McEnroe hung tough and 44 minutes later flung his arms into the air to celebrate his victory and walked to the net to shake hands with the disconsolate Borg.

For two days, McEnroe had fought Connors, Borg, and the crowd -- which cheered his mistakes to the very end -- and had come away the winner. "Any time you beat the No. 1 player in the world, it's something special," he said. t"But beating him to win the U.S. Open (and stop a Grand Slam bid) makes it even better."

For Borg, the defeat was crushing. He insisted it was disappointing like any other defeat, but his voice was flat when he said it. Not only had he lost the title he now wants most, but hehad lost it to McEnroe, the man who has succeeded Connors as his archrival.

"As long as I play tennis, I'll try to win the U.S. Open," he said, "It will be my biggest ambition in the future. At Wimbledon I was a little more lucky in the fifth set; today John was.

"I think in the future John and I will play a lot of great matches against each other. We have the best matches when we play. We play the best tennis when we are against each other."

Because of their Wimbledon masterpiece, the Borg-McEnroe rivalry had grown to almost mythic proportions in the public's mind before today. Now it is bound to grow even more.

"We don't play each other that often, that's part of the reason it's such a big deal," McEnroe said. "whenever we play, it's like here or at Wimbledon or the Masters, so there's a lot of attention and a lot of buildup. wI don't think we're bigger than the tournaments (as someone had suggested earlier). If we did that at Wimbledon the English would go grazy."

In the end, Borg, the Swede adopted by the New York crowd, couldn't wait to leave. He showered quickly, walked to the blue Saab his wife Mariana was driving and left without a word to the fans and groupies who trailed him, shouting encouragement and applauding.

McEnroe, booed in his home town, lingered, savoring his victory. Long after the match has ended he sat in the locker room with friends and enjoyed what he had accomplished.

"What does this say about me?" he repeated when someone asked him about the kind of courage it takes to win two magnificent four hour-plus five set matches in 28 hours. "It says I like to win."