For much of my life as a Minnesota Twins fan, the team's biggest rivalry was with the Oakland Athletics. Oakland had established themselves with a series of World series wins in the seventies, then when Tom Kelly became manager of the twins and Tony LaRussa took over the A's things really heated up. kelly and LaRussa were the best managers of their time, each could out maneuver pretty much anyone in the league except for each other.
Because of that, the teams' games were always played at a high level, no matter whether they were involved in a pennant chase or not. Then in the nineties the divisions were revamped, oakland in the West and the Twins in the Central, kelly eventually retired from managing and LaRussa moved to the national league.
But it's still fun when they match up. the Twins and A's now share similar circumstances, both are smaller market teams faced with larger market rivals in their respective divisions, and both are held up as examples of how to compete well even given that basic disadvantage.



