For 10 days, the Baltimore Orioles have held their breath and their tongues, pretending that each day was just another routine baseball game, that the stakes were not particularly high nor the hour late.

But today, minutes after beating the New York Yankees, 1-0, on Scott McGregor's elegant six-hitter and Terry Crowley's sixth-inning RBI double off Luis Tiant, the Bird locker room bubbled with the release of suppressed tension.

Correctly or not, the Orioles, who now trail New York by 3 1/2 games, believe today's vitory put them beyond the reach of significant Yankee damage. b

"This was the big one," said a jubilant Ken Singleton. "They can't get rid of us now. We'll be after them all the way, and we think we'll catch them.

"This means that we've won the eight games head to head either five to three or six to two, depending on what happens tomorrow. We're sure of gaining at least one game on them over this 11-day period. And if we win tomorrow, itLl be three games."

"Every guy on this team is certain that we'll beat out the Yankees for this championship, just as long as we don't bury ourselves in these head-to-head games," said pitcher Steve Stone.

"Sooner or later, our pitching will grind them down because we're better on the mound -- hands down. The last seven weeks, after we finish playing them, we'll play .700 ball. If it doesn't happen that way, call me a liar."

The Bird clubhouse that has been tight-lipped and cautious as a spy convention for a fortnight was openly jubilant and confident after a game so brilliantly clean and dramatic that it rivaled the tangled masterpieces that these clubs played in Confrontations 3 and 4.

The normally placid O's all stood yelling at their locker room TV set as they watched the replay of the final double-play grounder of this Baltimore clinic in pitching, defense and clutch hitting.

"Pick it, Doug," they called out as Doug DeCinces started his second far-ranging double play of the day, digging Eric Soderholm's grounder out of the hole.

"Throw it, Richie, Jeez. throw it," they cheered, laughing, as Rich Dauer had trouble making the final pivot.

Then, as the umpire called the last New York out with a fluorish, the O's went, "Aaaaawwww," as thought commiserating.

"Sorry, fellas," said reliever Sammy Stewart, talking to the despondent Yankees on the screen. "We can't play any more today. We're going to go in and eat some hot dogs," he said, stuffing his mouth with postgame food.

This game proved that the finest of all baseball scores is, indeed, the 1-0 duel that builds tension with every inning. McGregor was the master of anxiety today.

As McGregor went to the mound for this game which had the Orioles wearing their grimmest faces of the year, the pitching coach, Ray Miller, told him, "Work fast, throw strikes, and don't forget the charisma."

That undefinable thing -- charisma -- has been the last ingredient in making McGregor, now 14-6, one of baseball's best pressure pitchers.

"It took Scotty a while really to look in charge when he was on the mound -- you know, to get rid of the little-boy, what-am-I-doing-here look," said Singleton. "But, man, he's way past that stage now. Dr. Small can do it."

The most bomboozled New Yorker was Reggie Jackson, who had an enormously painful day, knocking himself dizzy by smashing into the right-field fence while making a marvelous run-saving catch, and striking out three times in an 0-for-4 performance against McGregor.

Those McGregor-versus-Jackson confrontations were the heart of this afternoon as 50,073 Memorial Stadium fans could watch blatant charisma and subtle charisma go eyeball to eyeball.

"I don't understand it," Jackson said. "He pitched to my power . . . he put it in my wheelhouse all day. I took pitches for strikes that I could have hit nine miles, and I swung through mediocre fast balls right down the middle. I just kept looking at him like I didn't believe it."

McGregor believed. He understands. It's called pitching.

"Reggie would llook at me and talk with his eyes," said a grinning McGregor. "He was saying, 'How'd I miss that ball.' And I was smiling back, saying, 'I don't know, but here it comes again.' I can't let him intimidate me.

"I know it's not reasonable that I can throw my (85 mile per hour) fast ball by him time after time. I'm as amazed as he is. But I'm going to stay with it until he hits one off the planet.

"Why do I keep challenging him?" chuckled McGregor. "Well, I like it and he likes it."

Evaluations of McGregor are changing every mounth. Since June 1, 1979, he is 27-10 and, as Singleton says, "It looks like now he's our best big-game pressure pitcher. And on this team, that's saying a lot. We've got Cy Young (Mike Flanagan), Cy Old (Jim Palmer), Cy Present (Steve Stone, the major's leading winner in '80 and Cy Future (McGregor)."

"You can't get no better than McGregor," said Earl Weaver, completely recovered from making a gilt-edged monkey out of himself the night before. He's not 'going to be' anything. He's there right now. A dozen years from now, there are going to be a couple of candidates for the Hall of Fame off his team, and McGregor is one of them. Hell, he's only 26."

Typical of McGregor's modest style is that he stayed in the trainer's room for 15 minutes after the game -- just looking at the wall -- so that veteran Crowley would have to get the lion's share of the attention from the first wave of a huge glut of national media types.

Crowley's hit -- a sharp grounder over the first-base bag that immobile Bob Watson waved at as though he were a statue toppling -- was freighted with double weight.

Not only did it eventually win the game, but it defused what might have been an enormously bitter controversy. Rich Dauer led off the inning with a blast that sent the ball into the first row of the left-field bleachers. wBut umpire Steve Palermo, involved in a battle with Weaver the night before, said a fan reached down into the field of play to touch the ball, thus making it a ground rule to double.

When Dauer was still perched on third with two out, ripe for stranding with two strikes on Crowley, that call looked like a potential subject for weeks of debate. But when Crowley lashed a jamming heater fair by inches, the issue became moot. "This team has been through a race together last year and gotten its feet wet," said Crowley, the grizzled king of swing. "I like what I see."

"Now, we just got two heroes (Dauer and Crowley), instead of one," growled Weaver.

The hero of heroes today however, was the unprepossessing McGregor whose charisma is all on the inside. "It helped my career last year to be in the playoffs and Series, to be in the tighest situation you can have in baseball, and be able to control myself -- shut everybody and everything out of my mind and be completely in command of myself."

McGregor is already a bit of a gutsy cult figure. Yankee Tommy John keeps McGregor's picture pinned beside his locker and says, "I just wish I had all the wins ahead of me that he's got coming."

The contrast between McGregor, who let only one man to third base all day, and Jackson, who was his prime victim, was as stark as the difference between buffs of a refined string quartet and an opera.

When Jackson blasted into the fence today, causing distressed Yankee bullpen denizens to actually climb the seven-foot fence to get to him, those here hardly knew how to feel.

"You really want to know my gut reaction?" said one Oriole. "I hoped he was dead. I just can't stand him."

McGregor was instantly concerned, but Weaver snapped, "He's just playing it for the dramatics."

"If he's alive," snarled another Oriole, "he'll milk this show for 45 minutes."

The Baltimore crowd, the folks who once cheered the announcement that Mickey Mantle's ankle was broken, booed the indubitably courageous Jackson both walking groggily off the field and, the next inning trotting back out to his position.

"Above and beyond all the self-selling tatics that make Reggie so hard to swallow, you gotta give him one thing," said Miller. "He's an $800,000 player who's willing to end his career just to catch one important fly ball.

"The only way he could have made that play any better, was if he'd leaped over the fence and landed on (relief pitcher Goose) Goosage."