Turn the tables
To turn the tables means to reverse the position against adversaries or opponents during a contest and so get the upper hand. The expression dates in this sense from the early 17th century and derives from games like backgammon, which in medieval times was called ‘tables’. Thus, the tables referred to have nothing to do with dining or card tables. The tables here are the mathematical variety. In fact, an early form of Roman backgammon was called ‘tabula’ after a mathematical table. The expression grew out of games like these when it meant simply turning the ‘tables’ around, figuratively speaking, i.e. looking at them from the opponent’s point of view in order to get the upper hand.