ACE IN THE HOLE

{n. phr.} 1. An ace given to a player face down so that other players in a card game cannot see it. * /When the cowboy bet all his money in the poker game he did not know that the gambler had an ace in the hole and would win it from him./ 2. {informal} Someone or something important that is kept as a surprise until the right time so as to bring victory or success. * /The football team has a new play that they are keeping as an ace in the hole for the big game./ * /The lawyer's ace in the hole was a secret witness who saw the accident./ Compare: CARD UP ONE'S SLEEVE.