When the invitation came last month for Michael Simon to box at the Goodwill Games here, he was sparring at the No. 10 Police Boys and Girls Club on 14th Street NW in Washington.

"I wasn't surprised," said the 17-year-old amateur boxer, who has all of 14 fights under his belt. "They wanted the best to represent the United States. They had to pick me."

Today, Simon was in the ring against Bulgarian Nikolaj Lapkov, his first foreign opponent in his first international bout, on his first trip abroad. "I wasn't scared," Simon said afterward. "There wasn't any time for that. If I'm going to take home a gold, I had to beat him."

Three rounds later, in a 4-1 decision, Simon was declared the winner and advanced to the semifinals in the light heavyweight competition. He knocked Lapkov down in the first round and won rather easily.

"I always knock them down," he said. "Basically, I damn-near beat him with the jab alone. I don't mean to be too immodest, but I'm marvelous. I'm just a baby."

Simon -- one of 23 U.S. boxers at the Goodwill Games and one of 13 to advance to the semifinals -- was named to the team after the Department of Defense, in a last-minute decision, barred nine members of the team -- all military personnel -- from coming to the Soviet Union for the Games. The Games are cosponsored by the Turner Broadcasting System and the Soviet committees for sport and radio and television.

The Defense Department "said it was basically a commercial venture and they didn't want the military to be taking part in that kind of thing," said Leslie King, director of communications for the American Boxing Association. "I'm not sure why they made the decision."

Of the nine replacements selected by the ABA, four are from Washington -- Simon, Lorenzo Wright, Tyrone Washington and Ricky Royal. Of the four, only Washington had traveled abroad before or fought in an international bout.

Washington lost last Thursday in the preliminaries.

Royal, after a Sunday victory, lost to Soviet boxer Alexandr Ostrovskij tonight. "He did well," said Keith Harrison, his coach from the M-Pac gym in Washington. "He was just a little cold."

Wright, 24, a fish cutter at the Safeway on Van Ness Street and Connecticut Avenue NW, fights Thursday in the 165-pound division. "I was shocked" at being chosen for the Games, he said. "I thank God for the opportunity to take part."

Wright, who started boxing six years ago, spars regularly at the Takoma Langley gym in Takoma Park, Md. For him, competing at the Goodwill Games was "an honor" and "a big chance."

"It's an honor to represent your country here," he said.

Considering himself too old to shoot for the 1988 Olympics, he sees the Goodwill Games as giving him his last chance for an international medal before he turns professional. "I'm going for the gold," he said.

Instead of his regular 10-mile run up 16th Street NW to Silver Spring, Wright is training for his matches with a daily two-mile jog along the Moscow River, followed by push-ups and sit-ups.

Since the boxing started last week, he has taken a place in the stands, wearing a Budweiser hat with buttons of Soviet historical figures and the Kremlin stuck in it. Within shouting position of the ring, he, Washington and the others cheer their teammates on against stiff competition from the Soviet Union, Venezuela, Mozambique and other countries.

The U.S. team suffered a setback today, when Soviet referee Yuri Frolov disqualified U.S. light heavyweight boxer Harvey Richards during his match against Denmark's Nils Hausgaard for a low blow.

The U.S. team filed an official protest. "The rules are that you can be disqualified for a low blow only if it is deliberate, or the opponent is incapacitated," King said. "In this instance, neither is the case."

A television tape of the disputed blow showed that it definitely was low, but it did not appear to be intentional. Pat Duffy, a manager of the U.S. team, said, "He Richards could have lost a point on an unintentional ruling, but intentional, no way. I think it the referee's decision was an honest mistake. The fight should not have been stopped. The referee overreacted or misinterpreted the rules."

"I think it took something out of the team as a whole," said U.S. 126-pound boxer Anthony Johnson, after beating Venuzuelan David Griman, 3-2, in the semifinals.

Simon, like Johnson, is preparing for big bouts later in the week.

"I sleep well, I eat well and I pray," Simon said. "I'm going to win."

He did admit that adjusting to the food had been difficult. "I'm living off that can of tuna we brought with us, and a little Hi-C," he said. "We don't even get mayonnaise.

"But I'm still going to win."

Simon's competition Thursday will be Nurmagomed Shanavazov of the Soviet Union, a European champion this year.

The biggest surprise of the day was the elimination of heavyweight Michael Bent of Cambria Heights, N.Y., who was outpointed, 4-1, by Soviet Vladimir Belai. The American heavyweight ranks were wiped away when Ike Padilla of Yonkers, N.Y., was stopped at 1:57 of the first round by Soviet Ramdan Sibiev.

The Soviet Union advanced 21 boxers to the semifinals.