Arthur ashe, the U.S. Davis Cup captain, has been saying all week that "nutty things happen in Cup competition." Ashe's words rang true today when American John McEnroe, the Wimbledon champion and No. 2-ranked tennis player in the world, lost in straight sets to Czechoslovakia's Ivan Lendl, ranked fourth in the world.

But Jimmy Connors barely broke a sweat in walloping Tomas Smid, 6-3, 6-1, 6-2, in the second singles to even this best-of-five quarterfinal competition with the defending Cup champions at a match apiece.

"I played pretty well out there; no doubt about that," Connors said. "Knowing that John lost the first match probably made me more eager, more aggressive," Connors said. "We couldn't go down, 2-0, especially on Arthur's birthday (Ashe was 38). I was surprised to see John get beat."

McEnroe, who won the Wimbledon men's title last Saturday, played miserably before 17,445 fans at Louis Armstrong stadium. The young left-hander made more unforced erros this afternoon than he did in a fortnight at Wimbledon. McEnroe said his two-week battle in England wore him out, physically and mentally.

A much more rested Lendl, playing on a fast, asphalt surface that is foreign to him, outlasted a quiet McEnroe, 6-4, 14-12, 7-5, in a 3-hour 15-minute duel that stunned stadium court fans who loudly supported McEnroe.

"I wanted to do well because this is the Davis Cup," McEnroe said afterward. "It's hard to explain this match. I'm just looking forward to a chance to play better on Sunday against Smid."

With McEnroe's loss, Saturday's 1 p.m. doubles match between Smid and Lendl and Stan Smith and Bub Lutz becomes pivotal. Smith and Lutz have lost only once in 13 Davis Cup matches. Sunday afternoon, Connors will try to continue his mastery of Lendl and McEnroe will face Smid.

McEnroe had plenty of chances to win the first two sets. He broke Lendl at love to lead, 3-1, in the first, but Lendl broke back, then held at 3-3, then broke the poor-serving American agan to lead, 5-4. Lendl held his serve, four points to one, to take the first set.

Lendl's usual strategy of staying close to the base line and provoking long rallies worked throughout that first set because McEnroe couldn't, or wouldn't, come to net. In that set, Lendl was successful with 60 percent of his first serves, which helped keep McEnroe back. McEnroe made only 44 percent of his first serves, further reducing his opportunities to come in.

McEnroe uncharacteristically hit nine straight back-court shots during one rally without trying to come to net. Even when McEnroe did come in, he seemed to stroll, never showing the eagerness he did in pouncing on Bjorn Borg's every offering at Wimbledon.

"I saw from the very beginning that he was trying to conserve energy," Lendl said."He didn't run and jump for every point."

In the second set, an uninspiring marathon that wasn't nearly as exciting as the score might seem to indicate, McEnroe broke Lendl's serve to lead, 4-2. The crowd, the largest ever to see a Davis Cup match in the United States and fourth largest in the history of Cup competition, began cheerig McEnroe loudly at every opportunity.

"It was nice to get a hand for a change," McEnroe said later.

But he failed to hold serve, netting two volleys and hitting a forehand into the alley. Lendl then served his way to a 4-4 tie, forcing the two into a 1-hour 45-minute second set in near-100-degree temperatures.

Lendl survived one set point against him at 4-5 by smashing one of seven aces past McEnroe and went on to even the set at 5.

Each player held serve for the next 15 games, with few inspiring points played. After McEnroe held for a 10-9 lead, the crowd stood and gave him a prolonged standing ovation, apparently hoping to inspire him to break Lendl and even the match.

McEnroe started with a crisp volley, then forced Lendl into an error for a love-30 lead. But Lendl evened the game with an overhead and a perfectly hit topspin lob. McEnroe then made two more unforced errors and Lendl held serve as the set went to 10 games each.

With the set tied, 12-12, Lendl was tiring McEnroe by running him from side to side. With the Czech holding advantage on McEnroe's serve, Lendl hit a backhand that appeared to hit the line and scoot past McEnroe.

But the lineswoman called it out and the umpire upheld the call, pulling McEnroe to deuce. The two players had retired to the sideline, assuming that Lendl had won the game. The Czech had to play three more points before breaking McEnroe and taking a 13-12 lead. He served out the next game to take a two-set lead.

The third set was a test of endurance. The players had already been on the court more than two hours. But it was Lendl who was supposed to wilt. Almost nobody, including the Czech captain, Antonin Bolardt, had given Lendl a chance to outlast McEnroe on the asphalt, which intensifies the heat.

Lendl, however, after losing in the first round at Wimbledon, had gone to Florida to practice to accustom himself to the heat and humidity he had never become adjusted to in Czechoslovakia, and that trip paid off today.

"I'm in good shape," Lendl said. "That was the most important thing in this match. By the end, he was tired. He played so long and hard at Wimbledon while I was in Florida for 10 days practicing three-hour drills every day against left-handers to get used to him."

McEnroe played well to begin the third set, taking a 3-2 lead and finding his way to the net a bit quicker than before. Leading, 5-4, McEnroe hit a forehand that Lendl couldn't return, taking a 15-0 lead. McEnroe turned to the crowd and opened his arms, as if to say, "It's about time I did something right."

But he continued to make unforced errors and Lendl held serve to level at 5-5. Lendl broke McEnroe to lead, 6-5, then closed out the match by flicking a cross-court forehand past a boldly charging McEnroe.

"I'm sure John had a tremendous emotional and mental letdown following Wimbledon," Ashe said. "He feels good, but hardly like going out to play tennis; especially with all the controversy that has followed him around."

Ashe seemed content to be tied, 1-1, going into Saturday's doubles. "Strategy A was to beat Smid twice and win the doubles," Ashe said. "By the first match on Sunday (McEnroe versus Smid), it should be all over."