Opening day should be ballons and banners, skydivers and standing ovations. It should be an idyllic afternoon set aside for saying hello to baseball once again, not worrying yourself sick about it.

However, for the Baltimore Orioles - the bargain Birds of the free-agent era - nothing comes that easily.

"Everything flashed through my mind in the ninth inning," said relief pitcher Don Stanhouser after he had saved the O's 6-5 victory over Milwaukee in the first game of the year at Memorial Stadium.

"I was really tight. I was overthrowing. I felt like the whole team was counting on me. When I got the last strikeout and 36,000 people started yelling, I stayed out there on the mound a little longer. I wanted to savor this rascal."

Should that sort of tension surround a leisurely home opener? You bet it should when the team in question is the jerryrigged Orioles, a young and vulnerable bunch that lost its first five games of the season by a disastrous cumulative score of 49-15.

"Stanhouse knew how much we wanted and needed this son of a buck," said Manager Earl Weaver. "All the markers were on him, all the pressure."

Seldom has one small victory meant so much to a team that won 97 games the season before.

"We needed to straightened out, and I mean right now," said Doug DeCinces.

"I'm not relieved," the relieved Weaver said with a grin. "I still feel like we're 1-5. But I also feel like a lot of things finally went right today." Those right things included:

A victory by one fo the O's infant pitchers, Dennis Martinez, who survived a shaky but determined 7 1/3 innings.

A nail-biting relief job by wild Stanhouse, who got the last five outs. "It wasn't pretty," he said, "but it was sweet."

A five-run rally in the bottom of the third after Milwaukee had jumped on Martinez for four runs in the top of the inning.

Superb Baltimore defense that included a double-robbing stab by first baseman Eddie Murray, a clutch double-play pivot by Billy Smith and a vital double play on a ninth-inning line drive by right fielder Carlos Lopez.

The Brewers had the crowd of 36,086 booing and grumbling when Paul Molitor singled home two runs off Martinez in the third and the next batter, Don Money, crashed an 0-2 pitch into the left-field bleachers for a 4-0 lead.

"The best thing that's happened all season is coming right back with five runs," said Stanhouse.

"My pitcher (Lary Sorensen) only has himself to blame," groused Brewer Manager George Bamberger. "How can you walk the seventh and ninth hitters when you have a four-run lead?"

Between those walks was an infield hit by Rick Dempsey that Money kicked at second.

"Our weakness is real shaky defense," said Milwaukee Coach Frank Howard. "We sure showed that today."

After Al Bumbry rang up the first Bird run with a bases-loaded single to center, the Brewers started their giveaway.

First baseman Cecil Cooper made a nice snag of Smith's hard grounder to his right, then fired the ball directly to left fielder Larry Hisle on two hops. Shortstop Molitor watched the spectacularly wild throw to second fly far over his head.

"Cooper's throw is the best break we've had all year," said Weaver.

One Bird run scored on the Smith Fielder's choice, a second on the crazy throw, and the Baltimore runners advanced to second and third as Hisle's peg to the plate skipped to the backstop.

Instead of getting one out, and perhaps two, the Brewers had made two errors, allowed two runs and set the stage for two more.

After Ken Singleton struck out and an intentional walk to Eddie ("I don't feel like anybody can get me out") Murry, Lee May quickly got himself in a two-strike hole.

"The way he swings at bad pitches, I thought we had him," said Bamberger. But Sorensen hung a high slider and May banged it over the second baseman's head for two runs that put the O's ahead for good.

"If May strikes out on the 0-2 pitch, we lose," said Weaver. "It's that simple."

Martinz, given a lead, found his gumption and challenged the Brewers (with their .322 team batting average) for four shoutout innings.

The Brewers may blame their defense for this loss of the year, but in his heart Bamberger probably is pointing the finger at himself.

In the seventh, Mark Belanger singled and was bunted to second. With two out, Bamberger let the tiring Sorensen pitch to Singleton.

Singleton punched an opposite-field single for what looked like an insurance run. It proved to be the winner.