TORONTO, SEPT. 15 -- Every few nights, just when the Baltimore Orioles start thinking their cycle of injuries, bad luck and terrible performances is complete, something else happens.

Tonight, it happened to rookie second baseman Bill Ripken, who tore a ligament in his right ankle during the first inning of a 6-2 loss to Mike Flanagan and the Toronto Blue Jays before 27,192 at Exhibition Stadium.

Toronto's win, coupled with Detroit's 9-8 win over Boston, left the Blue Jays and Tigers tied for first in the American League East Division.

Ripken caught his spikes in the artificial turf while chasing Tony Fernandez's grounder. He appeared to land squarely on the ankle as it twisted beneath him.

He was carried from the field on a stretcher and taken to Mt. Sinai Hospital, where X-rays showed no break or dislocation. However, it appears he'll become the fifth Oriole to suffered a season-ending injury.

This may be the worst loss of all because the youngest Ripken had been one of the Orioles' few bright spots in a season in which they fell 20 games below .500 (62-82) and 25 games out of first place for the first time in 31 years.

He was brought up July 11 in a desperation move, one made only after Rick Burleson and Alan Wiggins had failed at the position. He was coming after only a half-season at Class AAA Rochester and responded, not only with outstanding defensive play, but a .308 batting average.

"Don't write me off yet," he said. "This doctor here said I was done, but I'm going to see one in Baltimore Thursday. You never know. This is the worst feeling in the world, sitting here being interviewed when you're hurt. I hate it."

He'll probably have the foot placed in a full cast when he returns to Baltimore and said of the injury: "My spike caught and I couldn't get it out. My momentum carried me right on top of it. I felt it pop and heard it. It wasn't a pretty sound."

The Orioles had once suspected he might never be able to put together a healthy season, especially after he was injured in each of his first four pro seasons. But he stayed healthy for 141 games at Class AA Charlotte last year and had been healthy this year until tonight.

The Orioles had expected him to compete with Pete Stanicek for the position next spring, and Stanicek will now be given the job for the last 18 games. In a quiet clubhouse, the Orioles accepted their latest bad news as if they were hardly surprised.

"He sure had been a bright spot," Orioles Manager Cal Ripken Sr. said. "I don't know if we're due for any good luck in 1987."

After the game resumed, the Orioles continued their free fall as the Blue Jays followed a record-breaking 10-homer game by hitting two more, running their record to 87-57. The loss was the eighth in a row for the Orioles, who've had three losing streaks of at least seven games.

Flanagan (2-0 for Toronto) made his third start and was excellent again, allowing no runs on five hits in eight innings. The Blue Jays got him from the Orioles hoping he could make a difference in the pennant race, and he has, having allowed two earned runs in 21 innings with the Blue Jays (an 0.86 ERA).

It was the weirdest of nights for Flanagan, who was pitching against the Orioles for the first time since being traded two weeks ago. The trade came after he spent 15 years in the organization and, to fight his emotions, he refused to watch the Orioles taking batting or infield practice.

The only pregame interruption came when someone from the other dugout sent a note over that said: "We're going to get the old man."

"I heard a few comments during the game," he said, "but not that much. I think getting the five runs early helped everything. I didn't have the luxury of getting early leads in Baltimore, and when you get them it changes everything. This was probably the most difficult start I'll have to make here because of who it was against. Basically, I wasn't going to surprise them, and they weren't going to surprise me. I don't know if I was nervous, but I did want to get out there and throw the first pitch."

Rookie Jose Mesa (0-2) made his second start for the Orioles and was kicked around for 10 hits and four earned runs in four innings. Lloyd Moseby had four RBI and three hits, including his second homer in two nights. Catcher Ernie Whitt, who homered three times Monday, had only one tonight, and now has six in his last 16 at-bats.

Mesa, acquired in the Flanagan trade, again impressed the Orioles with his 94-mph fastball, but as was the case at Class AA Knoxville his control was all over the place.

"I was just behind too much," he said, "but I think I can do it next time."

The Orioles hardly came close to scoring against Flanagan, getting only one runner to third. He also made the pitches when he had to, leaving runners on second in the fourth, sixth and seventh innings. Duane Ward pitched the ninth, and the Orioles scored twice.

Cal Ripken Jr. walked with one out, and Ray Knight doubled. Jim Dwyer scored Ripken with a groundout, and Knight scored on a single by Larry Sheets.

The Blue Jays had runners on in every inning against Mesa. They got a 2-0 lead in the second as Willie Upshaw scored when first baseman Eddie Murray misplayed Rafael Liriano's grounder. Liriano scored on Moseby's triple to center.

The Blue Jays made it 5-0 in the fourth when Upshaw singled, Liriano doubled and Moseby homered over the right field fence. It went to 6-0 on Whitt's 18th homer in the fifth.