go downhill

• (General Australian) IPA^(key): /ɡɐʉ dɐʉnˈhɪɫ/

• Audio (General Australian):

  (file)

go downhill (third-person singular simple present goes downhill, present participle going downhill, simple past went downhill, past participle gone downhill)

1. (idiomatic) To worsen or degenerate.

   I usually run fast enough, but my speed goes downhill when I don't sleep enough.

• go to pot, go to the dogs; go to shit (vulgar), go pear-shaped