There were some whispers around the tennis circuit last fall that newlywed Bjorn Borg might have lost some of his singular determination to win tennis matches; that he was ready to settle down, start a family and not be so concerned with embellishing the record that already distinguishes him as one of the greatest players of all time.

Don't believe it. Listen, instead, to Lennart Bergelin -- Borg's longtime coach and confident, trainer and practice partner -- who insists that such speculation is pure twaddle. The remarkable Swede running short on motivation at age 24? Ridiculous.

Basketball Coach Bobby Knight has said that the much-celebrated "will to win" is the most overrated factor in sports, that the real cornerstone of sucess is the "will to prepare to win." The crucial thing, Knight preaches, is the wherewithal to put in more time and effort in practice than anyone else.

Bergelin agrees. "The day that Bjorn says he is going to take a shortcut and only practice two hours instead of four because that is enough, then I will know it is finished," said the coach who has been with Borg for more than a decade. "When he tries to get by on less work than he needs, it will be over. We are not there yet. He knows what he must do. Successful people must have interest for the job. He likes his job."

Bergelin's role has changed over the years. Once a Swedish Davis Cup player and Wimbledon quarterfinalist, he was Borg's mentor, guide to life on the circuit and coach in the technical and tactical sense. Now he is more travel agent and road manager, seeing that flights and practice courts are booked, arrangements made, rackets properly strung and phone calls screened. He is a friend and crafty ally, looking for every edge, as much a corner man for Borg as Angelo Dundee is for Sugar Ray Leonard.

"Before we were talking all the time about forehands and backhands, and I was a god for him," Bergelin said. "Now, I'm just there so there are no intrusions." Bergelin was talking about the art -- and, for him, the pleasure -- of being Borg's trusted handler on Wednesday, after his man's opening victory over Jose-Luis Clerc in the $400,000 Volvo Grand Prix Masters Tournament at Madison Square Garden.

This is the start of a new season, as well as the final playoff for the top eight performers of last year, and Bergelin said that Borg is eager to play again after a layoff of nearly two months. He is keen to protect his No. 1 world ranking, to win more majestic matches against Johm McEnroe and the ascending Ivan Lendl, to win his sixth French Open and Wimbledon titles to seize at last the elusive U.S. Open, and to continue compiling a record that may ultimately establish him as the premier tennis player in history.

"We're doing more or less the same things we were doing when he started with competitive tennis 10 years ago. We are pretty concentrated each match. We take it pretty serious," said Bergelin, 55, a big balding and eminently likeable man known on the tour as Kojak.

"We practice in the right time; we try to win the matches even in practice; we look at the schedule and prepare correctly. Of course, my job today could be a little more to try to make sure the interest is still there, because if you lose a little bit of interest and practice less, you are in danger.

"Sometimes Bjorn is saying,"I have been playing already 10 years,' and asking me how long I was playing, things like that. Maybe it is a little harder for him to keep up the interest. That's normal. But when he stops for a few weeks and then starts to play again, he is keen. Everything is all right. He has some years left, I think."

Bergelin pooh-poohs the suggestion that Borg's marriage to Romanian player Mariana Simionescu last July hs taken the edge off his competitiveness.

"You know how people gossip. They make something of the fact that Borg didn't win a tournament for more than three months after his wedding. He defaulted to Lendl in the Canadian Open final after injuring his knee jogging during his honeymoon, then lost to McEnroe in the U.S. Open final, his first defeat in a match that went five sets since 1976. In the autumn he lost to Lendl in five sets in Switzerland, and to Bill Scanlon in Japan. People are talking."

Bergelin laughs heartily at the notion that marital bliss has somehow changed Borg. He points out that Borg and Mariana were globetrotting companions for four years. The Borg-Simionescu-Bergelin trio was the tennis tour version of "Three's Company" all that time, and very little has changed.

"We get along pretty good," Bergelin said, understating the case."Mariana is good for Bjorn. He has someone to be with, to talk about their future life. After the tennis, they more or less go to their room and I go to my room. In the morning, we get up and practice.

"There's no problems. Mariana is always 100 percent on his side, on the side of his tennis. That is No. 1. She understands that as a player very well. She learned pretty quick, in the beginning, when they met each other in 1976."

Bergelin, for example, does not have to drag Borg to practice when Mariana would rather take him shopping.

"Never, never. That's never happened," Bergelin said. "It's very relaxed that way. She understands that tennis comes first, and I am happy that she is there because at the end of the day each one goes to the room and closes the door.

"I think that's great, because it can be too much sometimes if a player and coach are together day and night. . . Sometimes I go with him in the evening and play cards or something like this, but that's all."

They play casino, Bergelin said, and Borg hates to lose at any game. "He's counting the cards very carefully, you know. He knows what's going on," said the coach.

Perhaps fatherhood some time in the future will diminish Borg's interest in tennis, Bergelin hypothesized, but he thinks as long as the Swede maintains his zest for practice and physical conditioning, he will remain a world beater.

"If you are in good physical shape, you can be a very nice person off the court and a killer on the court. It is only when you don't have conditioning, when the skin is not hard and the legs are not good, that the mind gets loose," Bergelin said. "So far, Bjorn is in very good shape and is working very hard."

Bergelin knows this first hand from their practice sessions. "The last time I won a set from him was some years ago," he said, his blue eyes sparkling. "Now, he doesn't even give me games. If he could win every ball, that would be perfect for him. We are very good friends, we play every morning, and still he is trying to kill me."