急转直下 [- - zhí xià]a sudden turn [change] for the worse; a sudden change of circumstances;a sudden development of the situation; go into a precipitous decline; rapid deterioration of a situation; take a sudden decisive turn; turn abruptly towards a new vista:
•¶ 前方的军事局势急转直下。 The military on the front went swiftly ahead.
•¶ 股票市场行情急转直下。 The stock market turned down sharply.