ace up (one's) sleeve

A secret advantage. My stamina is the ace up my sleeve for this race—the other runners don't stand a chance! The defense attorney waited for just the right time to play the ace up her sleeve—a new eye-witness.

Common Names:

Name	Pronounced	Usage
Armando	ahr-MAHN-do (Spanish, Italian)	Spanish, Italian, Portuguese
Philon	-	Ancient Greek
Chi (2)	-	Mythology, Western African, Igbo
Cadoc	-	Welsh
Malcom	MAL-kəm	English
Nicholas	NIK-ə-ləs (English), nee-ko-LAH (French)	English, French