the best part of the show is yet to come; also used figuratively to mean that the most exciting, significant, or intense part of a situation has not yet happened.

Literally "when a mouse drags a wooden shovel, the big head is at the back"; means that the most significant part of a situation or the most serious trouble is still to come.

(idiom) the mantis stalks the cicada, unaware of the oriole behind (from the Zhuangzi); to pursue a narrow immediate gain while neglecting a greater danger nearby