have got an ace up (one's) sleeve

have got an ace up (one's) sleeve

To have a secret plan, idea, or advantage that can be utilized if and when it is required. A reference to cheating at a card game by hiding a favorable card up one's sleeve. I've got an ace up my sleeve for this race—my stamina. The other runners don't stand a chance! I hear that the defense attorney has got an ace up her sleeve—a new eye-witness.See also: ace, have, sleeve, up