yī​zhāo​bù​shèn​mǎn​pán​jiē​shū

one careless move loses the whole game

一着不慎,满盘皆输 一著不慎,滿盤皆輸 yī​zhāo​bù​shèn​mǎn​pán​jiē​shū
one careless move loses the whole game
One wrong move at a critical point leads to total defeat; a proverb derived from chess used to describe how a single mistake in a key step can ruin an entire endeavor.