ANAHEIM, CALIF., AUG. 10 -- The nearly unthinkable and virtually inexplicable are becoming everyday avenues to losses for the Baltimore Orioles. Such was the case again tonight, as the first run ever charged to reliever Gregg Olson in August produced a 2-1, 10-inning loss to the California Angels.

Pete Harnisch and Bert Blyleven, separated by a generation and a dozen or so mph on their fastballs, began the evening by staging an unexpected and captivating battle of wills on the Anaheim Stadium mound. Kent Anderson ended it with a one-out single after Olson had walked the first two hitters in the 10th and left with a 3-0 count on pinch hitter Johnny Ray.

Reliever Curt Schilling finished walking Ray, then gave up Anderson's line drive to center field after getting Brian Downing to pop out. It was the third time this year that Olson (5-4) failed to finish a game in which he pitched.

The Orioles lost for the fourth time in five games and fell to 54-57. They had six hits off Blyleven and Willie Fraser tonight, and have scored 10 runs in five games. The Angels, winners for the fourth time in seven games against Baltimore this year, are 54-59. Fraser (4-3) won with four innings of two-hit, no-walk relief.

Blyleven mastered the Orioles for six innings, allowing four hits and one run before departing with a stiff right shoulder. But Harnisch, whose season had been spiraling steadily downward since a 5-1 beginning, was his equal, yielding four hits, five walks and one run over a laborious seven innings and 120 pitches.

He struck out eight and was stung only by a third-inning home run by Max Venable, an outfielder who couldn't make the roster of the 1988 Orioles team that lost 107.

Blyleven traditionally has been an Orioles nemesis. He entered tonight's game with 20 career victories against them, more than any other active pitcher. His knee-buckling, jaw-dropping curveball always was a more-than-formidable foe for the Orioles' relatively free-swinging clubs of years past.

This struggling 39-year-old is not the Blyleven of previous seasons, as his 8-7 record and 5.41 ERA coming into this game suggest. His curve, once considered the best in the game, has lost some snap, and hitters lay in wait for his mediocre fastball. "He's always been able to adjust when the hitters have adjusted to him," Angels Manager Doug Rader said before the game. "It remains to be seen whether he can do so again at this point in his career."

Blyleven was superb a year ago -- when he went 17-5 with a 2.73 ERA -- and he seemed to have retained that magic upon winning six of seven starts in late May and early June. But his last seven outings before tonight yielded one victory, as he gave up 34 earned runs in 34 innings and failed to survive the sixth inning six times.

On a team reluctantly making the transition from a veteran club to one infused with some youth, he increasingly was beginning to resemble a spare part.

Don't try to tell that to these Orioles. They knocked him around rudely the past three years, but he worked 12 2/3 innings against them in back-to-back starts in May without an earned run.

He can survive and even thrive versus Orioles hitters because their patient, disciplined style at the plate does them more harm than good against Blyleven's craftiness.

He breezed through the Orioles' lineup in the early going, spotting his fastball effectively to get ahead in the count, then getting batters to swing at curves in the dirt. Catcher Lance Parrish helped him in the first inning by throwing out Steve Finley as he tried to steal second, and Blyleven wriggled out of two-on, one-out trouble in the third. But those were the Orioles' only semblances of a threat the first five innings.

He retired 10 in a row between Rene Gonzales' single in the third and Finley's two-out double in the sixth. But Cal Ripken followed that hit with a sharp, run-scoring single past diving third baseman Anderson to compensate for Venable's earlier homer and tie the game, 1-1. Counting an inning last season, it was the first earned run Blyleven had allowed the Orioles in 18 1/3 innings.

Meanwhile, Harnisch also was doing his part to craft an unlikely pitchers' duel. At 23 he is the AL's youngest pitcher with more than seven victories, but that has come about largely because the Orioles have provided him with almost six runs per start.

He began tonight with a 5.57 ERA over his previous 13 starts, and he had pitched only 1 1/3 innings in 12 days. But he was tenacious tonight, working out of several early jams to keep the Orioles in contention.