He continued to play the next two years as the third-string catcher before serving as Dave Duncan's backup 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.