play trump card

play (one's) trump card

To use a particular stratagem or resource that will give one a distinct advantage over others, often by being held and then used at an opportune time. I have a feeling the prosecution still hasn't played their trump card in this trial—I'm expecting a big revelation during tomorrow's testimony. I was looking like I would get full custody of the kids, but then Mary played her trump card—pictures of me going in and out of various women's houses around the city.
See also: card, play, trump
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.

play one's trump card

1. Lit. [in certain card games] to play a card that, according to the rules of the game, outranks certain other cards and is thus able to take any card of another suit. Bob played his trump card and ended the game as the winner.
2. Fig. to use a special trick; to use one's most powerful or effective strategy or device. I won't play my trump card until I have tried everything else. I thought that the whole situation was hopeless until Mary played her trump card and solved the whole problem.
See also: card, play, trump
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
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References in periodicals archive ?
Without a target man up front and left with only Rod Wallace and Gabi Amato - both happier playing off a natural predator - as strikers, the Dutch coach surely has to play trump card Albertzfrom the start.