The Cardinals had a party on the base paths for one inning tonight and almost everyone attended. When it was over, they had beaten the Atlanta Braves, 7-0, in the first game of the National League championship series.

Leading, 1-0, after five innings, the Cardinals scored five runs on six hits. They batted 11 men in the sixth inning to seal a victory in the first game of this five-game series.

The 11 hitters and six hits set a championship series record and the five runs in an inning tied another. In all, the Cardinals managed 11 singles in their 13 hits off four pitchers.

St. Louis starter Bob Forsch had two singles and a sacrifice fly, and gave up only three hits and no walks.

Dale Murphy of the Braves wasn't worried. "That was tonight and tomorrow is tomorrow," he said.

If the game imprinted a message on the Braves, who must win Friday's game (WJLA-TV-7, 8:15 p.m. EDT) or head home at an 0-2 disadvantage, it was the suddenness with which the speedy Cardinals can score, even when they don't steal a base.

The sixth inning started inauspiciously enough. St. Louis was ahead, 1-0, when Lonnie Smith (68 stolen bases in the regular season) led off with a grounder to first base. Chris Chambliss scooped up the ball, but his hurried throw to pitcher Pascual Perez, covering first, was at knee level and Perez dropped it. It was ruled an infield single.

That was the break the Cardinals needed. Keith Hernandez followed with a line single to left center, Smith moving to third. When George Hendrick singled home Smith, Atlanta Manager Joe Torre called on his ace long reliever, Steve Bedrosian.

Atlanta was still very much in the game, trailing only 2-0, but a walk loaded the bases with none out. Willie McGee and Ozzie Smith hit run-scoring singles to make it 4-0, with the bases still loaded and still no one out. Forsch's sacrifice fly made it 5-0.

The inning ended as it had begun. When Ken Oberkfell sent a two-out grounder to first, Chambliss caught it easily, but Bedrosian failed to cover the base. The Cardinals had their second single to first base, this one accounting for the sixth run.

It all happened so fast that one moment the Braves were in a game; the next they were surviving a rout.

Were they embarrassed?

"No," said Torre afterward. "Against a club like Whitey's (St. Louis Manager Whitey Herzog's), when they run and you don't cover well, you're disappointed, but not embarrassed. Our guys didn't roll over."

Torre said, "It wouldn't surprise me if Bedrosian was nervous (when he failed to cover first), but Perez pitched well. But we didn't play badly until we were way behind."

That would be in the eighth inning, when the Cardinals scored their final run on two singles, a fielder's choice and a sacrifice fly, a typical rally for them. The fielder's choice was a simple grounder to second with men on first and second, but Glenn Hubbard threw too late to force Tommy Herr and everyone was safe. That loaded the bases for the fifth time in the evening and set up the sacrifice fly.

The Cardinals had a laughable miscue of their own early in the game when Willie McGee, another of the many quick players on the team, pulled a third-inning triple over first base and into the right field corner. At least it wound up a triple.

McGee moved around the bases so fast he never bothered to look up at Chuck Hiller, the third base coach, who was madly waving him home. Hiller could see that right fielder Claudell Washington had taken a tumble in pursuit and the ball was still bobbling around in the outfield.

McGee, thinking triple all the way, pulled up at third and gave himself a quick handclap before realizing everybody was waiting for him to continue. By then it was too late.

Said McGee, "On a hit like that I'm thinking triple." Pity. With the Cardinals hitting only 66 homers in the regular season, this was a made-to-order inside-the-park homer.

Said Forsch: "You really couldn't print what I was thinking" when he saw McGee stop. McGee was saved further embarrassment when he scored the first run on a sacrifice fly.

Forsch said he had nothing special on his pitches tonight, but had good control.

Should this series go five games, Forsch is the likely choice to pitch the finale. Although that would give him only three days' rest and he hasn't pitched all year on fewer than four days' rest, Forsch said he would be willing to try.

The expectation is that the Braves will start Phil Niekro, the 43-year-old knuckleballer, in Friday's game, even though Niekro pitched Wednesday in the rained-out opener. He went 4 1/3 innings and gave up no runs, and when the game was called in a deluge, he told Torre he'd be willing to go right back out tonight.

Torre said he considered that, but decided Perez was a better choice. Tonight Torre said he was leaning toward pitching Niekro with one day's rest Friday, depending on how he feels after warming up. If Niekro does not start, the job will fall to Tommy Boggs.

John Stuper (9-7) is scheduled to start for the Cardinals. The series then moves to Atlanta for the final three games