The Soviet Union's hockey team scored four times in the first period and never looked back, routing the United States, 10-1, last night in Kennewick, Wash.

The Americans came into the game with high hopes after upsetting the world champions in an exhibition game last week. But they could not penetrate a strong defense led by goalie Arturs Irbe.

The Soviets are 2-0 and the United States 1-1 in the eight-team round-robin tournament. The Americans will move on if they beat West Germany (0-2).

Valeri Kamensky picked up a loose puck in front of the net and shot it over goalie Ray LeBlanc's shoulder 3:42 into the game. At 9:16, Alexander Semak scored for a 2-0 Soviet lead. Just 23 seconds later, Andrei Kovalenko was left alone in front of LeBlanc and he sent home a wrist shot.

Joe Sacco of Boston University scored the United States' goal at 4:40 of the third period.Big Upset for Reyes

What Javier Alvarez couldn't do, Sergio Reyes did.

Reyes, the United States' 119-pounder, scored the biggest upset yet in the boxing competition, beating reigning world champion Enrique Carrion of Cuba by a 3-2 decision and giving him his first loss in more than a year.

On a night that saw U.S. fighters in action against two Cubans holding world titles, Reyes evened the score for Alvarez's lopsided loss to Felix Savon in the heavyweight division.

"I wasn't at the world championships last year, but I feel I'm world-class too," Reyes said. "This was one of my biggest wins, but I've had others."

Reyes overcame persistent holding by Carrion and carried the fight to the Cuban to eke out a decision that delighted the crowd but surprised Carrion.

"I do feel surprised because all Cuban boxers go in to win, and if the judges call it the other way, it's a shock," Carrion said.

"They told me I had to go out and pressure him because he's the world champ and a close decision would probably go his way," said Reyes, who is the U.S. champion but did not compete in the 1989 world championships because he is a Marine and was stationed in Guam. "I felt he got tired in the third round."

The Cubans dropped to 3-3 for the games. The U.S. team improved to 11-5.Stull in Second

Anatoli Starostsin of the Soviet Union led the men's modern pentathlon with 2,195 points after shooting and fencing in the five-event pentathlon. He placed first in shooting, hitting 195 of 200 targets, and second in fencing. Second was Rob Stull of Damascus, Md., with 2,112 points. He won the fencing and placed ninth in shooting. . . .

The United States beat France, 15-12, 15-13, 9-15, 15-8, in volleyball. Versatile Craig Buck, who came out of retirement in June, had 12 kills and 12 blocks. He was supported by Uvaldo Acosta with 27 kills and Marc Jones with 26.

Joel Despaigne had a team-high 23 kills as Cuba beat the Netherlands, 15-10, 15-5, 11-15, 15-8. Italy beat Argentina, 17-15, 15-12, 15-12. . . .

Americans won the only two gold medals awarded in synchronized swimming.

Kristen Babb of Clayton, Calif., placed first in the solos with 98.80 points. In duets, twins Karen and Sarah Josephson of Bristol, Conn., the 1988 Olympic silver medalists, won the gold with a 98.88 score.