Hal McRae, John Mayberry and Al Cowens launched home runs yesterday afternoon in the first game of the American League Championship Series to get the Kansas City Royals off on the right foot against the New York Yankees, 7-2.

Last night, Dusty Baker provided the Dodgers with their second grand slam home run in as many post season games as Los Angeles evened its series with the Philadelphia Phillies with a 7-1 triumph.

While Kansas City's big boppers were providing the thunder, shortstop Freddie Patek, the smallest man in the majors, was right in the thick of each of his team's first two rallies.

The diminutive infielder led off the game with a four-pitch walk surrendered by Yankee starter Don Gullet, and then trotted home when McRae deposited one of the Cincinnati refugee's pitches over the left field wall.

Another Free Ticket

In the second, Gullett got himself in trouble with another free ticket, this one issued to Royal catcher Darrell Porter. Frank White handcuffed Graig Nettles with a shot to third, and both runners were safe when the third baseman's throw to second was late.

That brought Patek to the plate for the second time, and he laced a shot down the third base line into the corner. When left fielder Lou Pinella forgot about chasing the ball, thinking Patek had been awarded a ground rule double, both runners scored.

The Royals kept right on going in the third, Mayberry taking Dick Tidrow deep to stretch the lead to 6-0. The Yankees countered against K.C. starter Paul Splittorff in the bottom of the inning when Thurman Munson cracked a tworun shot.

Other than that, the Bronx Bombers were unable to do anything with Splittorff, a Yankee killer all year, and Kansas City held on to take a 1-0 lead in the five-game series.

Over in the National League, Baker's grand slammer came in the bottom of the fourth inning with the score tied, 1-1, and Jim Lonborg on the mound for the Philadelphia Phillies.

Ace hurler Don Sutton started for the Dodgers and went the distance, getting touched for nine hits but walking none on his way to the 7-1 victory. The series is tied, 1-1.