What Willie McGee does, when he hits the baseball, is run very fast. He runs so fast that sometimes he has his feet in high gear while his brain is in neutral. He laughs about it. "Maybe five years from now, I'll learn to watch the coach," he says. One such time tonight, Willie McGee ran so fast that he stopped because he figured a triple was all anybody could get on a ground ball to right.

The St. Louis Cardinals beat the bumbling Atlanta Braves, 7-0, on Bob Forsch's three-hit pitching in tonight's first game of the National League championship series. So pathetic were the Braves that, looking for a quick fix of confidence, they may start Friday night's game with knuckleballer Phil Niekro, using him on one day's rest after he pitched 4 1/3 innings in a rainout Wednesday.

Now the Cardinals have an enormous advantage in this series. Not only did they escape Niekro once, they now have an apparently unhittable Forsch ready for a late game. Some thanks goes, too, to the rookie McGee, a switch-hitting center fielder who scored twice and drove in an important run tonight.

He'll be remembered best as the kid who stopped at third base while the Braves still hadn't corralled his hit to right in the third inning.

Artificial turf makes a baseball field into a large pool table. Any shot well struck rolls true until it bumps into something. McGee screeched a hot ground ball down the first base line. On real grass, it's a double. Here, if the right fielder doesn't hurry, it's a triple.

So, rounding first, McGee saw that right fielder Claudell Washington didn't get to the ball in a hurry. Halfway to second, McGee set sail for third. By then he had his back to right field, and he never saw Washington fall down in clumsy pursuit of the ball.

It was a gift home run.

Only, McGee had stopped dead on third base, proud of himself for a triple. Washington hadn't picked up the ball yet. Before McGee came to, the ball was returned to the infield. McGee hung his head.

Whitey Herzog, the Cardinals manager, said, "Willie's one of the few guys I've seen run a home run into a triple. Willie just thought it was a triple. I thought Chuck Hiller (the third base coach) was going over and grab him."

In the warm glow of an easy victory, McGee saw the humor in his gaffe. When asked what Hiller said to him, McGee said, "At what time? When I got there? It wasn't too good."

Then he explained it. Because the ball was behind him, he didn't see Washington fall. And because he was thinking of a triple, getting set mentally to slide, he worried more about running than looking for directions from the third base coach. So he never looked for Hiller.

"That's why I messed up," McGee said. "When you're running fast, you don't always look."

In big games, even a third-inning base-running error looms important. Each of the 50,000 customers in the ballpark makes a mental note: tonight's award of goat horns goes to Willie McGee.

"If we had lost that run," Herzog said, "it might have changed the ball game."

McGee scored immediately on Ozzie Smith's fly ball.

"That took me off the spot," McGee said.

No such luck for the Braves, who twice couldn't complete one of baseball's basic plays, the pitcher covering first on a ground ball to the first baseman. Besides Washington falling in right field, first baseman Chris Chambliss fell down during the Cardinals' five-run sixth inning.

The Braves' bullpen threw high-octane, no-knock, $1.44-a-gallon gasoline on the fire started when the Cardinals rubbed six twigs of singles together in that sixth inning. Ace reliever Steve Bedrosian fed the conflagration with three hits, a wild pitch and a failure to cover first.

Someone asked the Atlanta manager, Joe Torre, if all this were embarrassing.

"We didn't cover first on one occasion, and we dropped the throw at first on another occasion, but 'embarrassing,' no," he said.

Of St. Louis' 13 hits, 11 were singles. The five-run sixth was a masterpiece of minimal offense. Eleven men went to the plate and none hit a line drive. Herzog has created a fleet team of pool table hustlers who take two bases on anything hit toward the corner pocket. The resulting tension renders opponents susceptible to anxiety attacks, such as Bedrosian's.

In 138 innings this season, he had not thrown a wild pitch.

"Double-A sometime, I'm not sure when," he said to someone asking when he last forgot to cover first base.

Two innings later, the flying Cardinals had the poor Braves so confused that twice they threw to the wrong base too late to do anything.

Torre called it "that inning when everybody kept running the bases and we kept throwing behind them."

At 3-0 in that disastrous sixth inning, Atlanta owner Ted Turner caught a foul ball. He owns a network, two major league teams and enough yachts to blockade Newport. The way he laughed about his newest possession, you'd have thought he had plucked the Hope diamond out of the air, not a $3 baseball.

Five minutes later, at 6-0, Turner left his seat and bounded up the stadium stairs, disappearing from view.