Dave McNally, a 20-game winner for the fourth season in a row, survived a rocky start to win the opener, which was delayed one day by rain.
It was at this point that A's manager Dick Williams made the first of several ultra-cautious moves which were to fuel criticism of his playoff strategy.
But Belanger rifled a single to center to score Frank Robinson and ignite thunderous cheering from the crowd of 42,621.
Then Curt Motton, pinch-hitter hero of a '69 Oriole playoff victory (Game 2) over Minnesota, stepped up to bat for McNally.
Skipper Williams was subjected to further sharpshooting for his failure to remove Blue, or even visit the mound, during the seventh-inning barrage.
Cuellar displayed his usual pitching artistry, a baffling assortment of curves and change-ups which the A's solve for a mere six hits.
Jim Palmer's performance in the deciding game was not among his most noteworthy—he permitted three home runs, two of them by the slugging Jackson and the other by Sal Bando.
But all three shots were struck with the bases empty, and Palmer had more than enough to pitch Baltimore's pennant clincher for the third straight year.
But in the seventh, Frank Robinson's double and Darold Knowles' wild pitch put Baltimore out of danger.