Baltimore Orioles relief pitcher Tim Stoddard learned today that the pain in his shoulder that forced him off the mound Wednesday "could be serious and could be lengthy," in the words of Manager Earl Weaver.

Weaver said Stoddard, who was due to fly to Baltimore Friday for tests, "more than likely will go on the disabled list," which throws into further turmoil Baltimore's reliever situation.

Stoddard, after visiting Boston Red Sox physician Arthur Pappas in Winter Haven, Fla., for a diagnosis this morning, said a muscle in his back evidently isn't working properly. Pitching apparently strained the shoulder muscles needed to compensate. "It's going to take a while to rebuild," he said.

Should Stoddard join starter Steve Stone on the disabled list it would leave the team with nine pitchers, the normal complement for opening day, but not the nine Oriole management had been counting on. Rookie Al Ramirez and revived veterans Ross Grimsley and Don Stanhouse would round out the staff. None of the three pitched in the majors last year.

Weaver said today he might send one of the three to the minors, and start the season with a pitching staff of only eight.

If there are holes in the pitching ranks, the Orioles will have to rely more on their hitting. As pitcher Sam Stewart, who believes the Orioles still have the best pitching in the league, put it, "In the past, we've said we're good pitchers but not hitters. This year, with (Dan) Ford, (Cal) Ripken and with (Rich) Dauer coming into his own, that's going to turn around. Even if we do struggle on the mound, the runs will make up for it."

This spring, the Orioles already have 22 home runs, 14 more than they had all last exhibition season. Gary Roenicke alone has three, including a ninth-inning game-winner Wednesday in Clearwater. That matches his regular-season total last year.

Veteran outfielder Al Bumbry said the addition of Ford, who had 21 homers and 101 runs batted in with California his last full season (1979), and the arrival of Ripken at third base, give Baltimore the best potential power in the lineup "since the days of Frank and Brooks Robinson and Boog Powell."

But Bumbry emphasized the word "potential." If each player lived up to it, he said, the team could count on 30 homers from cleanup man Eddie Murray, 20 each from Ken Singleton and Ford, 15 or 20 from Roenicke, who had 25 three years ago before breaking his wrist, and another 15 or 20 from Ripken. "That's more than 100 right there," he said. "We'd be in great shape."

The Orioles are sporting unusual bat strength in the infield, in addition to the first and second basemen. On the left side, the 6-foot-4 Ripken had 48 home runs in his last two minor league seasons,, and there's long-ball potential in Lenn Sakata, who hit only five homers last year but is batting .370 this spring, and in Bob Bonner, Sakata's backup, who is batting .349.

These all are supporting actors to the meat of the order, Singleton, Ford and Murray.

The addition of Ford will take the slow-footed Singleton out of right field and into the role of designated hitter. It also will juggle the lineup from time to time, with Murray moving to No. 5 instead of his traditional cleanup spot when the Orioles face some right-handers.

A question mark is the No. 2 position in the order. Dauer hit there last year, and said he expects to do so again this season. But Weaver feels Dauer, batting .235 this spring, has been going after high pitches and not drawing enough walks.

Lately, Dauer has been batting toward the bottom of the lineup. Weaver says he's likely to switch around on the No. 2 spot, picking the man who has the highest on-base percentage against the opposing starting pitcher. The idea, of course, is to get base runners for the heavy hitters to bring home.

The Orioles beat the Minnesota Twins today, 4-2, behind the four-hit pitching of starter Dennis Martinez and relievers Ramirez and Grimsley. Martinez, who will start against the Kansas City Royals in Baltimore opening day, gave up a run and two hits in four innings; Ramirez allowed a run and a hit, but walked four, in three innings, and Grimsley finished effectively. Singleton hit his third preseason homer.

The Royals have named Dennis Leonard as their opening-day starter, and Larry Gura will start Wednesday, probably against Scott McGregor. Tuesday is an open date.

The Orioles announced that about 3,000 seats, mostly obstructed views, remain available for Monday's 2 p.m. game