Ivan Lendl impressively overpowered Gene Mayer, 6-3, 6-4, today and Bjorn Borg beat Jimmy Connors in a lovely little war, 6-4, 6-7, 6-3, in the semifinals of the $400,000 Volvo Grand Prix Masters Tennis Championships.

Borg, the defending champion and undisputed No. 1 player in the world, will play the talented, ascending Lendl for a $100,000 top prize in a best-of-five-set final Sunday afternoon at Madison Square Garden (WDVM-TV-9, 3 p.m.).

The last time they met -- in the final of a tournament in Basle, Switzerland, on a similar indoor carpet last autumn -- Lendl won, 6-3, 6-2, 5-7, 0-6, 6-4, confirming the huge strides he has made toward the pinnacle of the tennis world in the last year.

Lendl's semifinal victory was like an air strike -- clean, efficient, requiring only 65 minutes of heavy firepower. The tall, sturdy, 20-year-old Czech Davis Cup hero was a bombardier, blowing the strangely flat and uninspired Mayer away with 14 aces.

Borg's eighth straight triumph over Connors in the past two years was more of an infantry assault; 2 hours 57 minutes of running and gunning and trench warfare. Borg slugged it out with his erstwhile arch rival from the back court for the better part of two sets before storming the net in the third. Some of the points were magnificent, pitched battles that had 17,985 spectators screaming and recalling splendid Borg-Connors confrontations of the past.

Borg these days is stronger than Connors in every way: off the ground, at the net, in the legs and between the temples. He wins points with his serve, which Connors cannot do, and has no glaring flaw like Connors' forehand approach shot, which betrayed the 28-year-old left-hander today as it has so many times since he owned tennis in 1974.

Borg now "owns" Connors and rules the empire that once was his, but Connors is still a lion-hearted fighter. He hasn't beaten Borg since the 1978 U.S. Open final, but he never, ever gives up. He pushed Borg today just as he did in a round-robin Masters match last year. Borg won that one, 3-6, 6-3, 7-6.

Connors hung tough today, too, saving a break point at 4-4 in the second set, getting to set point twice at 6-5 in an 18-point game full of bold and boisterous shotmaking, then winning the set in a tie breaker, 7 points to 4.

He seemed spent after that effort, falling behind, 1-5, and a match point down as his forehand collapsed completely. But he somehow gathered himself for a last stand after his backhand cross-court shot just clipped the sideline as Borg served at 5-1, 40-30. Borg thought the ball was wide and started to the net to shake hands, but he didn't get to match point again until two games and a major scare later.

Borg lost his serve for 5-2, and faced two break points when he served for the match again at 5-3. He saved the first with his seventh ace. He got a reprieve on the second when Connors missed his forte, a backhand, down-the-line passing shot, with an opening big enough to drive a tank through.

"When it comes down to the end, Jimmy gets more tougher. He is taking risks. I was lucky he didn't break me back for 5-4, because he had an easy passing shot," said Borg, who finally won on the fourth match point when Connors netted another forehand.

"If he breaks for 5-4, he is back in the match . . . I was surprised he missed that passing shot, because I thought it was pretty easy, but there was a lot of pressure on him then. Maybe he thought too much . . . This was the best Jimmy has played against me in a long time."

It was always an uphill fight for Connors, but he was in it all the way. There were five service breaks in the first set, four in the second, four in the third. Borg got only 53 percent of his first serves in court and Connors was returning serve superbly, often lunging wide to the backhand and driving the ball hard and deep, or angling it sharply cross-court, making Borg stretch for low forehand volleys.

In the first two sets, they had some truly rousing points. They were like hard-hitting welterweights exchanging their best punches: the tennis equivalent of the first Roberto Duran-Sugar Ray Leonard fight in Montreal. They were separated by 78 feet of court, but the pace of their shots made it seem as though they were toe-to-toe. The ball rocketed back and forth across the net like an electronic "Pong" game gone haywire.

Both men were intense, swift, and on top of the ball. Borg made a few astounding "gets" despite a blister on his foot that he had taped for protection and retaped after the ninth game of the second set.

Connors got 81 percent of his first serves in court, which precluded Borg from running around and thumping his topspin forehand return as often as he would have liked. But ultimately Connors could not hide his forehand; of the 33 points he lost, in the first set, 14 were surrendered on unforced forehand errors. Throughout the match, on the points that mattered most, it was his forehand that crumbled, especially the approach shot on which he so often forgets to stay low and follow through.

His return of serve and competitive heart kept Connors in the match. He was sprinting and stretching for every ball, lunging and diving with grunts, cursing and slapping himself to stay psyched up. Down, 1-5, in the final set, he kept hitting out, and almost pulled off a miracle comeback.

"At that stage, I'm just hitting cannons, all cannons, to see what happens.

He may get the shakes; you never know," said Connors. But in the end today, as it has been for two years now, his volcanic fire was smothered by Borg's glacial game.

There was no such palpable clash of wills and temperaments in the Lendl-Mayer match.

Said Mayer, "I just didn't have much 'oomph' the whole match. I didn't have any pizazz. I didn't feel bad, but I never felt like I could control the match. I was just kind of mentally tired." Mayer reached the semifinals by beating an ailing McEnroe, a fit Jose-Luis Clerc, and a tired and disinterested Borg.

Mayer is a sight to behold on court. He has an angelic, choir boy face; wears shorts that look like ill-fitting swim trunks, and heavy elastic bandages on both thighs to protect against recurring hamstring pulls; and plays with an oversized racket, hitting two-fisted off both sides. He is a master of touch, controlling points with variations of pace and spin, dinks, cleverly disguised angles and returns of serve chipped maddeningly to the shoetops.

But today he didn't have his rhythm. He was making far too many unforced errors, and eventually Lendl -- "6 feet 2 and still growing," a much more orthodox strokemaker with a big serve and topspin forehand -- bombed him out in admirably efficient fashion.