丢卒保车

Explanation: This is a chess term. After losing the secondary metaphor, to keep the main. 　　Usage: Joint type; as predicate; with compliment 　　Source: Peking Opera "Longjiang Song" first: "To save the dry river blockage, we will lose a number, saying that as we play chess, called 'lost a pawn to save car'." Thesaurus:  give up a pawn to save a chariot; sacrifice something minor to save something major