There's always something. John McEnroe was serving at 4-3 in the second set against Jose-Luis Clerc, who was making his first appearance in the Volvo Masters tournament. McEnroe had already saved one break point in the game and was serving the second. The first serve was a let. The second kicked wide to Clerc's backhand. The umpire, Frank Hammond, called, "Double fault."

There was a pause before he realized his error and said, "Excuse me, second serve." For the first time in the match, and perhaps the tournament, the crowd at Madison Square Garden began to get involved. It stamped and hollered and hooted. McEnroe paced. "C'mon Louie," a Brooklyn voice yelled. Ken Farrar, the Grand Prix supervisor, was summoned and a conference ensued. "The delay was caused by the chair," Hammond said. "You must replay the point."

Finally, the point was played, and McEnroe lost it, netting a soft forehand. The set was tied, 4-4. The match had become a match. "The people just wanted to get involved," McEnroe said, after winning, 6-3, 6-4. "There was nothing else to get involved in."

McEnroe, who is seeded fourth, will play Guillermo Vilas, the second seed, in a semifinal Saturday. Vilas, who has just completed a four-city exhibition tour with McEnroe (losing three times), defeated Andres Gomez, 7-5, 6-4, today.

Early on, McEnroe, who has been working to improve his demeanor, was in total command of himself and the match. He had varied the pace, and shot selection, playing often to Clerc's backhand, and then, when Clerc least expected it, to his more potent forehand. Although he was not pleased with his serve (he made 50 percent of his first serves), he volleyed well and played his ground strokes well.

Clerc, who was not serving well, either (47 per cent on his first serves), finally broke in the fourth game of the second set, to lead, 3-1. But on break point in the fifth game, he was called for a foot fault on his first serve and then double-faulted.

"I completely lost my concentration," he said. "The umpire made a mistake. It is never good for me. I say, 'Okay, this is the last point I play here because there is no way to beat McEnroe tonight."

Perhaps the biggest question of the day concerned the missing man, Bjorn Borg. Published reports in the Italian sports newspaper Tuttosport said that Borg, who is currently in Bangkok, intends to retire. Borg's agent, Bob Kain, of the International Management Group, said, "I can't confirm or deny it. There's been so many rumors since he's been out of it, we're used it . . . No one knows (what he is going to do) because he hasn't told anyone. I'm not going to say it's absolutely totally untrue because he hasn't told anyone."

Kain said Borg would be in the U.S. at the end of January to play exhibitions Feb. 2-5, and will then go to Toronto for an eight-man tournament. He is scheduled to play in a tournament in Brussels in March.

Asked if he would be surprised if Borg retired, Kain said, "I wouldn't be shocked, no. He just took a year off. Whether you come back, you either love it or you're out of the groove."

McEnroe said he would not be surprised, either. "I don't know if he has the desire to come back," he said. "It takes a lot of desire. You have to be motivated . . . "