在千钧一发之际
zài​qiān​jūn​yī​fà​zhī​jì

in the nick of time

  1. 在 zài preposition
    [location/time]
    Used as a linker to introduce the time, place, or situation of an action, meaning "at", "in", or "on".
  2. 千钧一发 千鈞一髮 qiān​jūn​yī​fà
    to hang by a thread
    a thousand pounds hanging by a single hair; used to describe a situation that is extremely critical or perilous
  3. 之际 之際 zhī​jì locative
    at the time of
    (bound form) at the moment when; during the time of