Andres Mora is extremely strong and knows it, to the point that "every time I go up I try for a homer."

Mora used his brute strenght to hit homer No. 7 today and it carried the Baltimore Orioles to a 5-4 victory over the Oakland A's before 9,579 damp enthusiasts.

The Orioles trailed, 3-2, when Mora came up in the sixth inning with two on and two out. The A's Doc Medich threw Mora a low outside fast ball and the 22-year-old Mexican reached down and lined it over the 405-foot sign in center field.

"It wasn't a good pitch, but it wasn't a bad pitch earlier," Medich said with a shake of his head. "It was away and down pretty good.

"I was really surprised he was able to hit it out. When he hit it, I just thought it was a long fly ball. But it just kept going. He must have real good power."

Mora's power was enough to save Ross from his own early mistakes. The Oriole lefthander, who seems to throw every pitch ever invented except a fast ball, all but handed the anemic A's three third-inning runs.

The Orioles grabbed on singles by Lee May and Eddie Murray, sloppy fielding by left fielder Mitchell Page that enabled both to move up a base, a passed ball and Kiko Gracia's grounder to third.

But Grimsley, now 11-6. gave the lead right back in the third. With runners on the first and third Rodney Scott tapped the ball to the pitcher's left. Grimsley tried to grab it and throw home in one motion to get lead runner Larry Murray, but dropped the ball.

He recovered he heaved the ball, without looking, toward first base, vacant, since Eddie Murray had charged the grounder. Both runners scored and Scott ended up on third base. Marty Perez' fly to center scored Scott for a 3-2 lead.

"It was nice to see those runs go up," Medich recalled. "When you're pitching for the Oakland A's you know you're starting every game with the back to the wall because we don't score a lot of runs. You know one little mistake will probably kill you."

Medich, who dropped to 5-6 in his 11th unsuccessful attempt for his sixth win since June 1, made that mistake in the sixth. Walks to Ken Singleton and May had set the stage.

"That is what you call major league power," said Oriole manager Earl Weaver, who was treated to an obscene version of "Happy Birthday" (47) by his team following the game. "No question about his potential or his strength. He just has to learn not to chase bad balls."

Moral (6-feet, 197) has 24 hits, 12 for extra bases, since returning to the Orioles June 3 from Rochester. A large mouthstache dominates his swarthy face, making him look years older than he is. But his exuberance betrays his age.

"I know if I hit it, it goes out," he said in his halting but improving English he spoke no English when he first joined the club in 1976. "It was a fastball and I hit it went."

A large smile crossed his face as he finished explaining his fest. But it wasn't quite that simple for the Orioles who trail Boston by 2 1/2 games. The A's, who have baseball's third-worst record and a batting order that would embrarrass many Triple A teams (no one over 300, only three men over 250) looked fairly solid for a while with their one-run lead and Medich pitching.

After Mora's shot disappeared over the fence, Medich stood motionless, hands on hips, staring at the spot for several seconds.

"I knew I'd blown it," he said. "We don't come from behind very often."