Mike Shannon's home run off Whitey Ford boosted the St. Louis Cardinals to a 9-5 win over the New York Yankees in the first game of the World Series yesterday.

The Cards entered the sixth inning trailing the Yanks 4-2 as a result of Tommy Tresh's two-run homer in the second. But Ken Boyer singled and with one out, Shannon whacked a 450-foot blast off the left-field scoreboard in St. Louis' Busch Stadium.

Tim McCarver followed with a double, knocking out Ford and bringing in Al Downing. The reliever gave up a pinch single to Carl Warwick and a triple to Cart Flood to give the Cards a 6-4 lead.

The Yanks made it 6-5 on a pinch double by Johnny Blanchard and a single by Bobby Richardson in the eighth. But the Cards put it away in the bottom half of the same inning with three unearned runs of Roland Sheldon and Pete Mikkelsen.

With two out and Shannon on second, manager Yogi Berra ordered an intentional walk for pinch-hitter Bob Skinner. Flood singled in one run and Lou Brock's double scored two more to make it 9-5.

Today's game, with Bob Gibson pitching for St. Louis against the Yankees' Mel Stottlemyre, will be broadcast by Channel 4 and WEZE radio (1260) at 1:45 p.m.