BALTIMORE, AUG. 18 -- The Oakland A's set a dangerous precedent for Baltimore pitcher Ben McDonald tonight. The A's became the first team to face the Orioles' phenom for a second time, and the A's apparently learned something.

In Oakland on August 8, McDonald beat the A's, 4-1, for his fourth win in as many major league starts. But tonight the A's got revenge.

"Seeing him once before helped a little," said A's first baseman Mark McGwire. "But he'll only get better. He's awfully big and he throws awfully hard."

The question is, will teams be able to figure out McDonald as they face him more often?

"Maybe. But he's going to start figuring out hitters too," said outfielder Rickey Henderson, whose two-run homer off McDonald in the seventh won the game, 3-1.

Henderson had a strained left hamstring and didn't play when McDonald beat the A's in Oakland, but said he watched carefully.

A's Manager Tony La Russa downplayed the significance of having seen the 6-foot-7 fireballer before.

"He's going to win a lot of games even after people have seen him," said La Russa.

And to be fair, the A's didn't exactly ravage McDonald -- in fact, he held them scoreless until the sixth. And were it not for one mistake -- a hanging curve to Henderson -- he might have won his sixth straight.

But even in defeat, McDonald continued to impress. "He's fantastic," said A's ace reliever Dennis Eckersley, who knows something about pitching -- his 38 saves, including one tonight, is second in the AL.

Some A's who failed against McDonald in Oakland said he was even better tonight.

"I actually thought he threw harder tonight," said McGwire, who was one for four with a single tonight. "It just came down to one pitch."

"Once you know what he's got and what his ball does, it helps a little," said A's third baseman Carney Lansford, who was one for four with a single tonight. "But with a pitcher with his ability, it's not much of an advantage. I can watch him all I want and see what his ball does, but that doesn't mean I'm going to hit him."

Center fielder Dave Henderson singled off McDonald and scored the A's first run in the sixth. He also struck out twice against McDonald.

"Once players start to get more and more at-bats against him," said Henderson, "it will be an indication of whether it's just a case of not knowing his stuff, or if he's just plain good."