Jimmy Connors angrily called Ivan Lendl "a chicken" early this morning, after the 20-year-old Czech stopped trying in the second set of the last round-robin match of the $400,000 Volvo Grand Prix Masters tennis tournament and lost to Connors, 7-6, 6-1, at Madison Square Garden.

Both Connors and Lendl already had qualified for this afternoon's semifinals with 2-0 records, and were playing for the dubious distinction of playing Bjorn Borg in the semis instead of Gene Mayer. Connors will now play Borg, and Lendl will face Mayer (WDVM-TV-9, 4 p.m.).

Connors won a good, combative first set in a tie breaker, 7-1, after saving set points at 30-40 on his serve in the ninth and 11th games. Then Lendl appeared to throw away the second set, which lasted only 18 minutes, much to the consternation of those who remained past midnight from the audience that originally numbered 15,781 spectators.

Lendl declined to attend a postmatch interview, but sent word through a spokesman that he "tried to change tactics in the second set, but that didn't work." Connors had a much harsher, and more realistic, analysis.

"I think he's a chicken. No matter what happens, you're supposed to try your hardest on every point," he told cable TV interviewer Marty Riessen. "I don't think what he did tonight was right.If you're Lendl you should try your buns off to play Borg."

Later, in a press conference, Connos was bitter and persistent in his criticism of Lendl. "I don't understand the guy's attitude," he said. "I want to win or lose fighting my heart out on every point. I don't understand why anybody would do what he did tonight. He's a rising young player with a future. He should be trying to make a reputation. That's not a way to make a reputation."

This was "morning-after" day in the Masters, a disgraceful time of forgettable, meaningless matches that emphasized the worst features of the hybird round robin-knockout format used in this playoff for the top point-winners of last year's Grand Prix tennis tour.

John McEnroe, already eliminated from contention for the semi-finals with a 0-2 record following his 6-4, 6-7, 7-6 loss to Borg in an exhausting match that ended 20 minutes after midnight Friday morning, looked like a sleepwalker when he went back on court 13 hours later and lost to Jose-Luis Clerc, 6-0, 6-3.

Borg, already assured a place in Saturday's semifinals with a 2-0 record, was similarly somnambulant Friday afternoon, losing to Gene Mayer for the first time in eight career meetings, 6-0, 6-3.

McEnroe and Borg were both sore, spent, weary, listless, and short on motivation. They found it difficult to get psyched up for a matches that meant nothing but a little extra cash, of which they have plenty. Their hearts, heads and legs wren't in it.

"I was trying my best but I had nothing to give," said Borg, who got to bed at 4 a.m. following his enervating victory over McEnore. "I was not in the match at all."

Borg's loss also raised a distrubing situation for the Connors-Lendl match. They went on court knowing that the winner would play Borg in the semis, and the loser would face Mayer, who is having a magnificent week (he beat McEnroe and Clerc as well as Borg), but is hardly as fearsome an opponent as Borg. Under the circumstances, it could be considered advantageous to lose.

Under the Masters format, the eight players are divided into two groups. Each man plays a round-robin match against the other three in his group. The two players in each group with the best records qualify for the semifinals, with the top finisher of one paired against the No. 2 man of the other.

Mayer finished atop his group with a 3-0 record, while Borg was second at 2-1. Connors and Lendl were both 2-0 going into tonight's match. Conceivably, the chance to play Mayer in the semis rather than Borg could be considered more valuable than the $10,000 bonus prize that goes to the winner of each round-robin group. (The winner of the Masters earns $100,000; the runner-up, $64,000; the losing semifinalists, $35,000 each.)

Lovers of the sport would like to think that players of Connors' and Lendl's caliber have too much pride of performance to stop trying in a match in order to pick their next opponent, and Connors demonstrated that he does. He gave a typically aggressive, all-out effort, and said afterwards it is not in his nature to do anything less. But Lendl's performance gave credence to cynics who had a field day predicting that he might stop trying.

He gave his all for a set.

It would be better for the sport if all such temptations were removed, and there were never an advantage, real or imagined, to losing. In the case of the Masters, this could be accomplished simply by deciding the semifinal pairings by lot after the four players qualified.

Tournament director Ray Benton of Washington acknowledged tonight that the flaw in the existing format "could raise suspicions," and said he would present alternatives to the Men's International Professional Council for their consideration in future years.

In Friday evening's first match, Guillermo Vilas defeated Harold Solomon, 5-7, 7-6, 7-5, giving an effort worthy of professionals even through neither had a chance to make the semifinals. Vilas and Clerc finished with 1-2 records and earned $20,000 apiece. Solomon and McEnroe finished with 0-3 records and collected $13,000 each.

Mayer and Connors are 3-0, Borg and Lendl are 2-1, and the Masters Tournament and Lendl, unfortunately, have black eyes.