The Orioles faced the Minnesota Twins in the American League Championship Series. In Game 1, Cuellar allowed three runs (two earned) in eight innings, leaving with his team trailing 3–2. Baltimore tied it in the ninth on a Boog Powell home run, then scored the winning run in the 12th on a Paul Blair RBI single to win the game 4–3. The Orioles went on to sweep the Twins three games to none en route to winning the American League Pennant and earning a berth in the World Series against the New York Mets. Cuellar again got the start in Game 1, allowing one run over four innings and outpitching Tom Seaver in a 4–1 victory. The two faced off again in Game 4; Cuellar pitched seven innings, allowing just a home run to Donn Clendenon, but the Orioles were losing 1–0 when Cuellar exited the game. Brooks Robinson tied the game with a sacrifice fly in the ninth, taking Cuellar off the hook for the loss, but the Orioles lost the game 2–1 in 10 innings. In the next game, the Mets completed one of the biggest World Series upsets ever, winning the 1969 Series four games to one against the heavily favored Orioles. Cuellar's triumph in Game One wound up being the only Baltimore victory.