機先 きせん せいする
kisen'o seisuru

Suru Verb
Expression

1. to beat someone to the punch; to get the drop on (someone); to forestall

連中 れんちゅうがこのことに きずかづかぬうち機先 きせん せいしたほうがいいでしょう。
renchūga kono kotoni kizukanu uchikisen'o sēshita hōga iideshō.
We'd probably be best off beating them to the punch before they notice that fact.