A-Game

In Elements of Poker, author Tommy Angelo defines "A-Game" as "when you play your best and feel your best at the same time." Often used to refer to players making decisions and performing at the highest level, either with reference to their own capabilities (i.e., the best one can possibly play) or in a broader sense (i.e., the best anyone can possibly play). E.g., "I was playing my A-Game, but the cards just didn't cooperate."