Reds, Davis Pull Rug Out on A’s, 7-0 : Game 1: Center fielder hits two-run home run in first inning. Oakland’s postseason win streak ends at 10.

It wasn’t a baseball game, it was a sucker punch.

With the Oakland Athletics comfortably settled into Riverfront Stadium Tuesday night for Game 1 of a series that is expected to lead to their second consecutive World Series championship, the Cincinnati Reds jumped them.

Eric Davis’ first-inning home run knocked them back. Jose Rijo’s teasing fastballs turned them around.

Big hits from Billy Hatcher and Chris Sabo in the fifth inning dropped them. Then Rob Dibble and Randy Myers, with two scoreless relief innings, finished them off.

The Reds ended up with a one-game-to-none lead in the 87th World Series with a 7-0 victory before 55,830 at Riverfront Stadium.

“People all around the world now know we’re for real,” said Barry Larkin, the Reds’ shortstop. “I think the A’s always knew. But if they didn’t, they know now.”

And how. Oakland’s 10-game postseason winning streak was snapped even though their best pitcher was on the mound, their best hitters came to the plate with runners on base, and their aura of invincibility had never seemed more secure.

After all, wasn’t this is a team that allowed the Boston Red Sox only four runs in a four-game sweep in the American League championship series?

The Reds scored four runs in the first three innings.

Wasn’t this a pitching staff that had walked only six Red Sox in those four games?

They walked six Reds in six innings Tuesday. Three of them scored.

Wasn’t this an great offensive machine that averaged five runs per game against Boston without even hitting a home run?

They still haven’t hit a home run in this postseason, and Tuesday they left 11 runners on base.

“Man,” Rickey Henderson said, shaking his head. “They beat us. I really don’t think we played that poorly. They just beat us.”

Hurting the most was A’s starter Dave Stewart, he of the menacing stare and career postseason record of 7-1 with a 1.98 earned-run average.

Today he is probably using those stares on the mirror. He couldn’t even make it past the fourth inning, allowing four runs on three hits and four walks.

The hits and walks were twice as many as he had allowed in two playoff starts. It was his shorting outing in nearly two months.

After the game, for once, he was asking the questions.

“I wasn’t even close tonight, and I can’t figure out what it was,” said Stewart. “If I knew, man, I would have fixed it as soon as I could. But I didn’t have that much time. It was four innings and lights out.”

Throwing that switch was Davis, who has been struggling with a sore shoulder and a knee that will require surgery after the season.

During the playoffs he batted .174 with only one extra-base hit and two RBIs. His last homer was on Sept. 26.

Then, with two out in the first inning and Hatcher on first base after a walk, Davis’ swung at Stewart’s first pitch.

Then with a boom that could be heard even behind the glass-enclosed luxury boxes, his luck, and the game, changed. The ball traveled high above the head of center fielder Willie McGee, clanging into a camera area 410 feet from home plate.

“Ball was right down the middle of the plate,” catcher Terry Steinbach lamented. “He hit it, I knew it was gone.”

Said Larkin: “The man smoked it. To have him come out like that after all the injuries he’s had, that was a huge lift. “

Davis became the 22nd player in World Series history to homer in his first Series at-bat, and one of the first players this year to seemingly beat the A’s in the first inning.

“That homer got them going,” Henderson said. “That was the turning point.”

“All I know,’ Davis said modestly, “is that it gave us the lead.”

More important, it turned Rijo giddy.

“I see that and I say, ‘Man, this is going to be our night,’ ” Rijo said. “I loved that.”

Then he pitched like it, rolling off what became seven scoreless innings in which he allowed seven hits.

He was not overpowering, he was worse. He was frustrating. He allowed 11 runners but no runs, throwing such powerful A’s hitters as Mark McGwire into a postgame funk.

With runners on first and third and two out in the third, he fooled McGwire into a grounder. With bases loaded and two out in the fifth, he fooled McGwire into a popout to second base.

“Broke my bat, just busted my bat, I don’t know what happened,” McGwire said of the popup. “I was trying to do too much with it, I guess, and it just busted me. Just popped the darn thing up.”

McGwire was asked about his career postseason average of .167, with only one homer in 60 at-bats, and he shuddered.

“I could care less about playoff stats,” he said. “They don’t mean a darn thing. Nothing. Everybody blows them out of proportion. Everybody is saying the big guys can’t hit.

“This is one game, man. Just one game.”

While some of A’s appeared stunned, other veterans shook their heads and shrugged. It was if they were glad their younger teammates finally learned, this team can be beat.

“I’m telling, anybody who thinks we can just walk on to the field and win is crazy,” Carney Lansford said. “We can’t walk over people, nobody can do that. We have to fight like we have all year. I’ve played on too many great teams that lost big games to know, this ain’t going to be easy.”

After Davis’ homer, it got harder for the A’s when Hatcher, who doubled twice and scored three runs, doubled in a run in the third inning after a walk to Larkin. Larkin scored on the double when Mike Gallego, who was replacing the injured Walt Weiss at shortstop, made an error on the relay. Then, Paul O’Neill’s grounder made it 4-0.

In the fifth inning against reliever Todd Burns, the Reds clinched it with a double by Hatcher, a walk to O’Neill, an RBI single by Dais and a two-run single by Sabo.

That left it to Rijo, who exacted revenge for three unhappy year in the Oakland organization from 1985-87.

“I didn’t have to show them I could pitch, I wanted to show my teammates I could pitch,” Rijo said, smiling. “I wanted to prove to everybody that pressure don’t bother me.”

The pressure is now, strangely, on the A’s.

“We have to win one here before going back to Oakland, so that means we have to win (today),” Lansford said. “Not that it’s do or die or anything, but we have to go out and get it.”