出其不意，攻其不备

chū qí bù yì , gōng qí bù bèichuqibuyi,gongqibubei

1. to catch an enemy off guard with a surprise attack (idiom, from Sunzi's "The Art of War" 孫子兵法|孙子兵法[Sun1 zi3 Bing1 fa3])

Study it in Yanamino