Boxer Eric Griffin, suspended for six months after marijuana was found in his system during the 1988 Olympic trials, opened his Goodwill Games competition in impressive fashion yesterday, taking a convincing 106-pound win over Alcis Bel Flores of Venezuela.

"I couldn't let my 10 years {of boxing} go down the drain," said Griffin, who was the only American to win a world championship last year in Moscow. "I just tried to get it off my mind and try and turn my career around."

Griffin, 22, was a second-place finisher in the Olympic trials, headed to a box-off against Michael Carbajal for a spot on the 1988 Olympic team when his drug test during the trials turned up positive.

Carbajal ended up winning the silver medal; Griffin stayed home in Houston and rededicated himself to the sport he took up at age 10.

"I kept training that whole time I was suspended," he said. "Ever since I've been training five hours a day, seven days a week."

Griffin also has stayed off drugs and, under the guidance of Houston computer software store owner Bob Jordan, kept away from the crowd he used to run with."It's been nearly three years and I haven't been doing any drugs, drinking or nothing," Griffin said.

Griffin lives with Jordan, who sponsors his amateur career and will guide him when he turns pro after the 1992 Olympics.

In other matches, U.S. light heavyweight (178 pounds) Jeremy Williams, in only his third international bout, knocked out Bulgaria's Ljubomir Agov in the first round.

Williams, 17, of Fort Dodge, Iowa, hit Agov with a thunderous right to the head in the final minute of the round. Agov sat down on the canvas then fell onto his back.

In the semifinals, Williams will face Soviet Andrei Kurnyavka, the 1989 world middleweight champion, who beat Hungarian Sandor Hranek when the referee stopped the bout in the second round.

American Terry McGroom also won a bruising fight in the light heavyweight class with a 3-2 decision over Sven Lange of East Germany. Powering Into Medal Round

Scott Hatteberg and Jorge Fabregas each drove in four runs as the United States clinched a spot in baseball's medal round by beating Mexico, 15-2, in Tacoma, Wash.

Hatteberg, a sophomore at Washington State, hit a two-run homer in the third inning and a single in the sixth for two RBI. He also singled and scored in the second inning.

"We knew Scott was a great player when we recruited him," U.S. Coach Jim Morris said. "I'm very glad things have worked out."

Fabregas's RBI included a leadoff homer and a two-run single, both in the second, when the U.S. squad scored seven runs.

Mike Hostetler allowed just three hits over the final five innings for the victory. He gave up five hits and two walks and had one strikeout. Ten of the 21 outs were on ground balls. Wrestlers' Rhapsody

The U.S. wrestlers pulled off a major upset Saturday night by defeating the Soviet Union, 17-13.

It was the first time in 30 years the United States had beaten the U.S.S.R. in a team competition that featured the best Soviet wrestlers.

The U.S. victory was not ensured until a protest by Soviet Coach Yargin Yarygin was rejected.

Although the United States had beaten the Soviets three times in World Cup competition, the top Soviet wrestlers weren't in those competitions, U.S. Coach Joe Seay said.

"I wasn't concerned with the protest. We came to beat the Soviets with our best team and we did it," he said. "They were at their best. It was the best Soviet team they could put together and we did it."

Four U.S. wrestlers won individual gold medals -- Cory Baze at 105.5 pounds, John Smith (136.5), Nate Carr (149.5) and Bill Scherr (220).

Scherr ended his career with a last-second, 2-1 victory over Andrei Golovko. "I was lucky to win," Sherr said, "but I'm a much better wrestler than him."

Sherr's brother Jim (198 pounds) lost, 2-0, to Makharbek Khadartsev.