noun
moment just before something happens; brink; verge
Almost always used in the set phrase 機先を制する (to take the initiative, to forestall). Rarely appears independently.
See also: 機先を制する
相手の機先を制して、有利に試合を進めた。
We took the initiative and gained the upper hand in the match.
交渉では、機先
In negotiations, it is important to forestall the other side.