BALTIMORE, OCT. 1 -- Somebody thought he heard the Fat Lady singing "O Canada."

The Toronto Blue Jays' last road trip of the season took them almost to oblivion tonight when the Baltimore Orioles rallied for three runs in the sixth inning and went on to a 6-3 victory before 24,442 at Memorial Stadium. The Jays tumbled two games behind Boston with two games remaining as the Red Sox beat Chicago to clinch at least a tie for first in the backward sack race for the American League East title.

"No matter what happens, this club will be heard from again," said a Toronto Manager Cito Gaston. But he looked and sounded as if he meant some other season than this one. For now, he agreed disconsolately, his Blue Jays will need a "miracle."

"That's the way the game goes," said left fielder George Bell, who had no specific answers as to why the Blue Jays have folded their wings or whether he'll be relocating in a new nest next season.

Almost cruelly for the Blue Jays, defeat was administered by one of their former farmhands, Jose Mesa. It was far from a perfect performance by the hard-throwing righthander, but it was good enough to help the Orioles at least partly avenge their lost division title hopes in the 1989 season-ending series at Toronto.

Mesa (3-2) got the victory tediously, going 7 2/3 innings, walking six and laboring through 119 pitches. But the rookie got hitters out when he was in trouble, then got relief help from Kevin Hickey and Gregg Olson, who recorded his 37th save by retiring the side in the ninth. The result was sweet for the Orioles, but especially bitter for Toronto.

"It's a lot of pressure, especially since those guys are in a pennant race," Mesa said. "There was a lot of pressure to throw strikes, which is why I think I couldn't throw my fastball for a strike. I didn't have my best stuff."

"We remember what it was like up there last year, watching them celebrate," said Randy Milligan, making his first Memorial Stadium start since separating his shoulder in a collision at home plate Aug. 7 in Oakland. "We won't let them celebrate on our field this year."

Clearly, the Blue Jays were in no mood to celebrate.

"It seems almost impossible," third baseman Kelly Gruber said, "but in this game anything is possible. We have to control what we can control, and hope for the best."

The best they could get now is a tie -- if they win two and the Red Sox lose two. That would force a one-game playoff Thursday in Toronto. But even the Blue Jays didn't talk like they expected to fill the SkyDome one more time.

"It's frustrating going out there with a comfortable lead and then to give it up like that," said David Wells (11-6). "I just got behind some hitters and that's something you can't do. They were looking for fastballs, and that's what they got."

The pitch Wells may think about long into the offseason was a 2-1 fastball to Mike Devereaux, who lined it over the left field fence for two runs to tie the game in the sixth inning. "We have to come out here tomorrow and do our job," was just about all Gaston could say.

Plagued by poor pitching, Toronto has managed to win only two of seven games on its closing nine-game trip. The staff has a 6.08 ERA for the trip.

Wells proved to be the latest failure. The Blue Jays scored twice in the first inning on an RBI single by Fred McGriff and a sacrifice fly by Bell. The Orioles got a run back in the second when Bob Melvin doubled home Jeff McKnight. Wells struck out Craig Worthington to avoid further damage.

In the fourth, Wells struck out Milligan swinging and McKnight looking with Cal Ripken at second. Milligan received a welcome-back ovation; in his first game off the disabled list -- the first game of Sunday's doubleheader in Cleveland -- he went went three for four with two RBI.

The Blue Jays made it 3-1 in the fifth when Gruber, batting .395 this season against the Orioles, doubled home Mookie Wilson from first.

Wells was done in the sixth. With Bill Ripken aboard on a walk, Devereaux knotted the game with his 12th homer of the season and fourth in 10 games. With one out Milligan singled, advanced as McKnight was thrown out attempting to bunt his way on and scored when Melvin singled for his second RBI.

Worthington greeted reliever Frank Wills in the seventh with a double to left. Running for Worthington, Juan Bell scored on Bill Ripken's single as big brother George Bell could only hold the ball in left field and watch.

Big Sam Horn made it 6-3 in the eighth when, batting for Milligan, he hammered a 1-0 pitch from Duane Ward over the left field fence and off the concrete stadium wall beyond the 360-foot sign. That gave Horn two pinch-hit home runs this season off Ward, who also gave up a three-run shot to Tom Brunansky Saturday at Fenway Park.

Horn's 14th home run set off a chorus of farewells to Toronto from Orioles partisans who remembered the ending to 1989. The laughter and song gave way to booing when Chicago's three-run eighth inning at Boston was posted. But Boston would yet make the night complete for Orioles fans.

After Olson set down Toronto in the ninth, he was mobbed by teammates -- as if they were in the race. It was, said Manager Frank Robinson, "a nice game to win. It's a game we . . . were looking forward to. . . . It's a nice way to close out the season."

Orioles Notes: Toronto outfielder Glenallen Hill had emergency surgery today in Boston for a ruptured appendix.