in 1971. Tenace entered the 1972 season backing up Duncan, but was given a chance to show his abilities by being made the team's regular catcher in the post-season. Tenace took full advantage of this opportunity, excelling in the 1972 playoffs and World Series. In the 1972 American League Championship Series against the Detroit Tigers, he drove in the clinching run in Oakland's 2–1 victory in Game 5; it was his only hit of the series. Tenace's heroics made up for an error in Game 4 of the series when he had to play second base (for the first time since high school) in the late innings due to regular second baseman Dick Green getting hurt and backup second baseman Ted Kubiak having to play shortstop due to Bert Campaneris being suspended. Tenace dropped a throw from Sal Bando on a potential game-ending double play attempt in the bottom of the 10th which kept the inning alive as the Tigers eventually won. He put himself in the spotlight once again in Game 1 of the 1972 World Series when the Athletics faced the Cincinnati Reds. He became the first player to hit home runs in his first two World Series at bats and drove in all three runs in the A's 3–2 victory. Prior to Tenace's feat, only eight other players had homered in their first World Series at bat. In Game 4, the A's were losing 2–1, with their only run to that point coming on Tenace's solo home run. A ninth-inning one-out rally consisting of four singles, with Tenace's the second and the rest coming from pinch hitters, won the game against Cincinnati's ace relief pitcher, Clay Carroll. He hit a three-run home run in the A's Game 5 loss. Before Game 6 of the 1972 Series, he was the target of a death threat. In Game 7, he was once again the hero, driving in two runs in a 3–2 victory for Oakland. In total, he went 8-for-23 in the Series, with four home runs and 9 RBI to earn the World Series Most Valuable Player Award. Tenace's heroics helped him earn a full-time job in Oakland's lineup. He served as the team's starting first baseman for two seasons, while still serving as the backup catcher to Ray Fosse. He had his roles reversed in , starting at catcher while backing up first base. As a regular