隙に

while there is an opening

→ 隙
phrase Rare #37,083
while there is an opening Used when taking advantage of a brief opportunity or someone's inattention. Often follows a clause or noun phrase, as in ~している隙に, meaning “while someone is doing ~.”
JA: 彼が寝ている隙に、そっと部屋を出た。
EN: I quietly left the room while he was asleep.

よいにはきっとひとつあるその隙にを集めて勝負をする

Every good castle has one weak spot; lure the enemy there and make your stand.

— 七人の侍 (1954)

この隙に

While we have the chance?

— ラブ・アクチュアリー (2003)

トムメアリーお風呂に入ってる隙に彼女の日記をこっそり読んだんだよ

While Mary was taking a bath, Tom secretly read her diary.

おいら引き付けるから-その隙に行けますかね

I’ll draw them away, so can you make your move while they’re distracted?

— 君たちはどう生きるか (2023)