"Casanas has a lot of pressure on him. He's bitter, I'm younger than he is. I've taken his world record. I've beaten him every time out. I've accused him of a rolling start. I gave him an opportunity coming to the Pan Am Games to beat me. I had nothing to prove here, just to run against Casanas. I gave him his chance; he had his chance. He lost his chance."

Renaldo (Skeets) Nehemiah

Just at dusk, with the last light of day behind the finish line and night behind the start. Renaldo Nehemiah and Alejandro Casanas got in the blocks.

They did not shake hands.

Sixto Escobar Stadium went silent. The high jump stopped. No one wanted to miss the grudge match of the Pan American Games - the showdown between the ill and shaky Nehemiah and the Cuban Casanas who has tried to psych and intimidate him for days.

The scoreboard reminded the crowd of the evening's first two events - a split in a sprint duel between the U.S. and Cuba.

Evelyn Ashford of the United States had won the 200 meters in 22.24 seconds to go with her 100-meter gold, while Cuba's Silvio Leonard had completed an identical double-gold for men, winning his 200 in 20.37.

Next, ironically, the big board flashed the listed world record in the 110-meter hurdles - 13.21 by Casanas, although Nehemiah had smashed that mark in April, May and June with marks that technically are still pending.

"I felt lightheaded in the trials," said the slender Nehemiah. "Tonight I was calm getting in the blocks, back into my pattern.

"I knew Casanas needed very edge and might try to beat the gun. If he rolled, I was going out, too."

Casanas needed that rolling start, but couldn't get it. Even with a jump, Nehemiah has caught and passed him four straight times. Tonight, Nehemiah was dead even at the first hurdle, in control after three, and romping at the fifth-hurdle midway point.

When Nehemiah crossed the finish, pumping a No. 1 finger over his head, he had beaten Casanas' lifetime best again with a 13.20 clocking and left the Cuban at least three yards behind - a large hurdles margin. Casanas' time was 13.46. Charles Foster of Durham, N.C., was third in 13.56.

In defeat, Casanas could not bring himself to be gracious. "I admire Nehemiah, but he's no superman," said Casanas. "Technically, I don't think he is very good."

That did it for Nehemiah, who has simmered ever since Casanas refused to shake his hand during a bad-blood run-in here at Escobar on Saturday.

"My form is good enough to win races and set world records. I can't be that bad," said Nehemiah with perfect self-control. "I came here to beat Casanas under the worst conditions - when I've been sick and still feel weak. I wanted to face and fight it out. Every race I am running now is like an Olympic final . . . I want to prove absolutely who is the best in the world.

"Nevertheless, I run against Casanas as a friend," Nehemiah forced himself to say. "One reason I can't have a feud with him is because I can't understand him. Tonight, after the race, when we went for our drug test, he finally shook my hand when I offered it. At least, that's a step in the right direction."

No doubt exists about Nehemiah's supremacy in his event, only about his future: Will he improve, maintain or frizzle?

"Casanas is right," said Foster. "Technically, Nehemiah does a lot of things wrong, but does 'em fast .

"If he could do those wrong things right and still do 'em fast, he could go down another two-tenths of a second," said the veteran Foster.

"If he'll just take a break now - and I've advised him to - he'll be all right. He has nothing more to prove for now."

It was Casanas who almost took a break tonight - in the middle of the race. Predictably, in defeat he claimed a minor groin muscle pull, limped off the track and said, "The pain was so bad I almost pulled off the track after the sixth hurdle."

"Gee, I wouldn't know about that," said a ginning Nehemiah. "I can't see behind me.

This was Nehemiah's night to bask in some justified self-pride. Speaking so eloquently, with never a "you know" or pause, that he might have written his polished remarks and memorized them, he hurdled many a subject - smoothly, of course.

"I will take a break now before the World Cup (the final week in August). I'm exhausted. I've had a lot of pressure on me. I've felt I was an unknown this year and had a lot to prove," said the University of Maryland sophomore.

"I feel like I'm the continuation of (Olympic champion Rod) Milburn - consistent. When you can count on yourself for a 13.3 every time, then, when you have to go down deep for a big race, you can pop a good one."

Tonight, Nehemiah reached deep on the worst of exhausted, ill evenings and popped one.

"This race told me a lot about myself," he said softly.

And then he sneezed.

Matt Centrowitz of Brooklyn, N.Y., survived a foul claim by Mexico and captured the third gold medal of the night for the United States by winning the 5,000 meters in a rather slow time of 14:01. Teammate Herb Lindsay of Lansing, Mich., finished second in 14:04.1 and Mexico's Rodolfo Gomez was third in 14:05.

The protest was lodged because Lindsay ran into Gomez near the 3,000-meter mark causing the Mexican to lose his balance. Lindsay, however, was the one who fell to the ground and dropped into fifth position. But he got to his feet and closed fast at the end to nip Gomez for second place.

Mexican officials argued that neither Centrowitz nor Lindsay would have beaten Gomez if the collision had not occurred. Gomez, however, argued with his own officials not to protest the outcome.

Mac Wilkins, the Olympic champion from Soquel, Calif., was an easy winner in the discus with a Games record throw of 207 feet, 8 inches. In breaking the Pan Am mark of 204-7 set by John Powell in 1975, the powerful Wilkins became the eighth consecutive discus champion from the United States since the Games began in 1951.

Franklin Jacobs, the diminutive junior from Fairleigh Dickinson University, outdueled Benn Fields of Salisbury Mills, N.Y., in winning the high jump, another event the United States never has lost in the Games, Jacobs set a Pan Am Record of 7-foot-5. The old Pan Am record of 7-4 1/2 was set by American Tom Woods in 1975.

Meanwhile, a Puerto Rican district judge ruled today that Bobby Knight, the short-fused coach of the American basketball team in the Pan American Games, must stand trial Friday on a charge of aggravated assault against a local policeman.

Assistant District Attorney Carlos Ramos Pantoya said Knight's counter charges of assault and battery, violation of civil rights and incarceration without knowledge of the charges had already been thrown out of court before today's two-hour closed-door session.

In other basketball news, star guard Kyle Macy of the unbeaten U.S. men's squad flew home to face surgery on his jaw, fractured by a Cuban opponent's punch Tuesday night.

The U.S. Olympic Committee charged the Cuban guard, Tomas Herrera, also was "the center of controversy during the 1973 World University Games in a game against the United States in Moscow."

In Baseball today, Cuba eliminated the United States with a 7-1 victory. The Cubans pounded three U.S. pitchers for 14 hits. CAPTION: Picture, Renaldo Nehemiah streaks to a gold medal in the 110-meter hurdles in Pan American Games record time of 13.20.