BALTIMORE, AUG. 19 -- The Baltimore Orioles' luck with injuries had long since run out when reliever Mark Williamson broke his right ring finger during Saturday night's 3-1 loss to the Oakland Athletics.

He went on the 15-day disabled list today, becoming the fifth Oriole -- joining infielders Bill Ripken and Randy Milligan and pitchers Bob Milacki and Dave Johnson -- to be shelved since July 30. On that date, Baltimore was one of only two American League teams that didn't have a player on the disabled list.

But that was then, and this is trouble for the Orioles, who recalled starter-reliever Jose Bautista, 26, a right-hander, from Rochester to fill the roster spot. Williamson (8-2 in 49 games) is Manager Frank Robinson's best set-up man for closer Gregg Olson, despite a recent slump in which he yielded 12 earned runs in his past 11 games.

"You're looking at my first broken bone ever," he said.

"I'm feeling good out there, I'm throwing the ball well and then this happens. We're dropping like flies."

While pitching in the ninth inning to Walt Weiss, Williamson slipped off the mound and broke the finger trying to brace himself for an awkward landing.

"I threw a change-up and it landed short," he said. "My weight carried over. . . . I knew it was broken as soon as I did it.

"It's a good indication when the finger is pointing in the wrong direction. It's a nice, clean break."

His fractured metacarpal bone could sideline him three to four weeks. His hand is in a cast.

Bautista's recall is the Orioles' eighth personnel move in 20 days, as he became the seventh player on the 25-man roster who wasn't here three weeks ago. He was 7-7 with a 3.65 ERA at Rochester in 26 games, of which 12 were starts.

"I've been working very hard over there, just waiting for something to {have the Orioles} call me up," he said. "I don't think about it too much. The feeling is really good there in Rochester."

In his previous two stints with the Orioles this season -- from opening day until April 22 and June 9-15 -- he was 0-0 in seven games.

He spent all of 1988 with the Orioles, going 6-15 with a 4.30 ERA. Last season, he was with them four times, going 3-4 with a 5.31 ERA in 15 games.

He defeated the A's twice in 1989, once in Oakland.

"I don't know how they're going to use me here," he said. "Starting or relieving is no problem." Milacki Progressing

Milacki, eligible to be activated Tuesday, threw about 15 minutes from a mound today, his third such outing since he went to the DL with a strained right shoulder -- and first session since receiving a cortisone shot Thursday.

"I threw a lot better the last time than I did this time," he said. "But this time I didn't feel any discomfort. The only thing was that I didn't know where the ball was going because of the shot."

He said it's unlikely he'll be able to pitch until the weekend, when the Orioles return from a three-game series at Boston for a seven-game homestand beginning Friday against Cleveland. . . .

Milligan appears to be handling his slightly separated left shoulder quite nicely. Although he isn't eligible to come off the DL until Aug. 25, he approached a reporter in the clubhouse today and said, "News flash: Milligan will be back in two days." . . .

The attendance for the weekend was 142,552, the second-largest total for a three-game series in Memorial Stadium history.