ace / card up one's sleeve

/ˈeɪs ˌʌp wˈɒnz slˈiːv/

/ˈeɪs ˌʌp wˈʌnz slˈiːv/

ace / card up one's sleeve

a secret advantage that a person can use when the need arises

Examples

1. The mayor's popularity among elderly voters gives him an ace up his sleeve for the coming election.

2. But they had an ace up their sleeve.

3. They had an ace up their sleeve: DATA.

4. His life as a fugitive did not last long, though, as Valpo had an ace up their sleeve.