Scott McGregor made Tony Armas look foolish on the first change-up he threw him in the seventh inning today. So he threw him another.

This time, McGregor looked foolish. Armas reached out and hit it toward the left field fence. Neither thought the ball would make the seats, but it did and the Oakland A's beat the Baltimore Orioles 2-0.

That's one way to lose a three-hitter, as McGregor (8-3) found out. His one mistake allowed Rick Langford to win with a five-hitter.

"He bowled 300," said McGregor, "and I bowled 298."

Langford allowed no walks; McGregor walked two. One of the base on balls proved costly when McGregor lost Cliff Johnson on a 3-1 pitch leading off the seventh.

Armas was the next batter. He was way out in front of McGregor's first pitch, a devilish change-up. The next change-up quickly became a fast ball going the other way for Armas' second homer in as many days, his third in five days and his 16th of the season.

None of the Orioles has homered in the first five games of this road trip.

Eddie Murray, Baltimore's leading home run hitter, sat out the game because he strained his left wrist in Friday night's game. Second baseman Rich Dauer didn't play because of a spike wound on his left hand picked up in the same game.

"I could have used Murray as a pinch hitter, but he couldn't field," said Baltimore Manager Earl Weaver. "How do we know how we would have done with them in the lineup? (Lenn) Sakata got a hit, didn't he?"

Sakata played second in place of Dauer.

After the game, Dauer and Murray were X-rayed at Oakland's Merritt Hospital and the results were negative. Trainer Ralph Salvon said the X-rays were merely precautionary and both players could have appeared in today's game.

"As soon as I picked up the ball today in the bullpen to warm up before the game, I felt right," said Langford, whose first shutout of the season raised his record to 7-8. "I felt good enough to do well, even if Eddie Murray had been in the lineup. Terry Crowley had done well enough against me in the past that Weaver stuck him in there against me."

Crowley went zero for four. He was robbed of a hit in the ninth on a sensational diving catch by left fielder Rickey Henderson.

"Their outfield is awesome," said McGregor.

"No doubt about it," said Weaver, going a little further. "That's the best defensive outfield I've ever seen together in this league. Not for hitting, although they (Henderson, Dwayne Murphy and Armas) hit all right, but defensive. They've got tremendous ability and speed."

And the A's pitching?

"I haven't said this in 14 years," said Weaver, "but their pitching might be as good as ours."

The A's never got more than one runner on base off McGregor in any inning and a runner as far as second only twice before Armas, the American League's RBI leader with 51, connected in the seventh.

The most serious Orioles threat came in the eighth when Sakata singled and went to third on Al Bumbry's one-out bloop double. Jim Dwyer lined softly to shortstop Fred Stanley and Ken Singleton hit the ball hard on the ground, but directly at second baseman Shooty Babitt, who was playing on the right field grass.

The loss dropped the Orioles three games behind Detroit in the Al East. The A's, meanwhile, are the only first-half winner leading their division (AL West) in the second season.