Jimmy Connors and Bjorn Borg, slugging away at each other in the final set of a tingling match, the crowd gasping on every point.

But this was not the Wimbledon final. Madison Square Garden's howling mob of 17,150 made Connors feel in his element, and he beat Wimbledon champ Borg, 6-4, 1-6, 6-4, to win the $100,000 top prize in the Colgate Masters Tournament.

Connors now has won eight of 11 career meetings with the 21-year-old Swede, and this was in the best tradition of their hard-nosed, thrilling rivalry. The 2 hour 50-minute match had a few commonplace valleys and some Himalayan peaks.

Connors - who had lost an epic three-set match to Guillermo Vilas in the round-robin portion of this final playoff for the top eight finishers in the 1977 Colgate Grand Prix point standings - today rose to the occasion and displayed the form that made him the dominant player in tennis from 1974 through 1976.

Connors came back from 0-2 in the final set, slugging his approach shots fearlessly to take command of the net and beat Borg from there.

Connors broke after four deuces in the fourth game - one of several matches within matches in the rugged, scintillating final set - and held from 0-30 in the next game. He won on the climb thereafter.

Borg held for 4-4 after four deuces and three break points in another splendid skirmish, but the slender Swede appeared to be getting weary and slightly dispirited. He hurried to be getting weary and slightly dispirited. He hurried over to Connors' side of the net between games for a quick sip of a drink.

Connors immediately pulled ahead, 40-0, in the next game, but let Borg back to deuce by overhitting a high, easy forehand volley. Then the 25-year-old lefthander from Belleville, Ill., bore down, creaming a backhand crosscourt winner off a high-velocity rally and following a forehand down-the-line approach in for a killing forehand crosscourt volley.

Connors had all his old swagger back now as he went out to receive serve after the changeover.

Borg won the first point with a good serve, but Connors came steaming in on the first short ball of the next fierce rally and clocked a forehand approach winner down the line: 15-15.

Every point was coming from an entrenched battle by now, but Connors backed Borg up with a wicked forehand from behind the baseline, followed in another forehand approach and won the point with a lunging backhand stop-volley: 15-30.

Borg netted a backhand off a side-to-side baseline rally to make it 15-40, match point. The crowd erupted, then fell into a hush as Borg stepped up to serve.

Connors waded in behind yet another forehand approach - a shot that has deserted him so often, but was as solid as Gibraltar most of today - and smacked a forehand volley winner down the line to end it.

Connors was hitting such killer volleys today that he seemed to be signaling that his taste for blood was back after a year disappointing only by his own lofty standards. He was the No. 3 man for 1977, behind Borg and Vilas, who beat Connors in a magnificent U.S. Open final.

AT the end, with the crowd stomping and cheering in appreciation, Connors raised his arms triumphantly and puffed out his chest. It was as if he ws delivering his New Year message: the King is dead, long live the once and future king. Then, after this momentary exultation, he shook hands and patted Borg on the back.

Connors went on court today eager for a showdown, aching to avenge that Wimbledon final in which he battled back from 0-4 to 4-4 in the fifth set only to unravel after a costly double-fault and lose, 6-4.

The 5-foot-10, 150-pound street fighter of tennis started exceptionally well. He was flying around the court in the first set, his feet and steel racket flashing as he slashed everything hard and deep.

He saved two break points in the second game and broke from 40-15 in the third, exploding two approach winners off short balls. The 40-30 point was significant because Connors crackled a backhand down-the-line passing shot on it as Borg came to the net for the first time. That discouraged the Swede, and he seldom came into the forecourt again.

That break held up for the first set, but the pace drained from Connors' shots and errors crept in as he lost eight of the next nine games, losing his serve four times in a row.

Borg seemed to have overcome an early sluggishness, and when he out-fought Connors in the first game of the final set, breaking him on his third break point, after five deuces and three Connors ads, he seemed to have his man caged.

That one game, 16 points consumed 12 minutes. It was full of ferocious exchanges - Borg sprinting along the baseline and Connors looking for a ball, any ball, on which to come in.

Borg had two net-cord winners, one for 30-15, another for his first ad. He looked apologetic. Connors fumed.

Finally Connors made an unforced forehand error and overhit a backhand approach to lose his serve. But he was conceding nothing.

He stuck in, and in the fourth game - with Borg struggling to hold serve in a similarly combative game - he got a net-cord winner of his own. On his third advantage point, Connors whacked a forehand that clipped the tape and climbed over for the break. When Lady Luck delivered the equalizer, it was on a big point.

Connors smiled and raised his hands triumphantly. Then he held from 0-30 in the next game with four fine shots, the last a good serve that forced a backhand return error.

Connors was back in the match, playing deliberatelt, letting the raucous screams and shouts of encouragemeny subside between each point. Mentally he apperred refreshed, while Borg was slipping. It was only a matter of time . . . and now Connors thinks 1978 is a very good year.

Coming into today's match, Connors had a 7-3 career advantage over Borg, but the Swede was 2-0 in 1977. He beat Connors, 6-4, 5-7, 6-3, in the finals of the Pepsi Grand Slam, a four-man television tournament, last January and in a magnificent final at Wimbledon, 3-6, 6-1, 5-7, 6-4, in July.

Borg won their first meeting, at the Stockholm Open in 1973, and then Connors won seven in a row, including the final of the 1976 U.S. Open.

Both finished 2-1 in the round-robin portion of the Masters.

Connors beat Eddie Dibbs, 7-5, 6-2, lost to Guillermo Vilas, 6-3, 3-6, 7-5, in a three-hour classic and beat Manuel Orantes, 6-2, 6-3. In Saturday's semifinals, he topped Brian Gottfried, 6-4, 3-6, 6-3.

Borg whipped Raul Ramirez, 6-4, 7-2, outlasted Roscoe Tanner, 6-4, 6-7, 6-3, and then defaulted his last round-robin match to Gottfried, claiming a "severe case of flue."

Borg beat Vilas, 6-3, 6-3, in the semifinals, thereby clinching the No. 1 world ranking for the 1977 season. Vilas had won 80 of his previous 81 tournament matches, but was 0-2 against Borg in tow 1977 meetings.

Vilas defaulted the third place match today, saying he did not want to risk aggravating a strained tendon in his left foot suffered late in his match against Connors. Gottfried collected third place money of $40,000, while Vilas got $32000.

In lieu of the third place match, Gottfried played Ramirez in an exhibition, which Ramirez won, 7-6, 7-6.

On Saturday night, South African Davis Cuppers Bob Hewitt and Frew McMillan won the doubles title, beating Stan Smith and Bob Lutz, 7-5, 7-6, 6-3, in 1 hour 56 minutes.

Hewitt and McMillan split $40,000, while Smith and Lutz split $20,000. The doubles Masters was a straight knockout competition for the four teams that topped the doubles Grand Prix standings.

Hewitt-McMillan beat John Alexander and Phil Dent in the semis, 7-6, 7-6, while Smith-Lutz beat Gottfried and Ramirez, 4-6, 6-3, 7-6.