off (one's) guard

Not being especially careful or vigilant; not prepared for danger or surprises; being careless or inattentive. He's got a lot of tricky moves, so don't be caught off your guard! We'll wait until he's off his guard, and then we'll take him and his company for all they're worth!

Common Names:

Name	Pronounced	Usage
Aldin	-	Bosnian
Mordad	-	Persian Mythology
Alister	-	Scottish
Amelia	ə-MEE-lee-ə (English), ə-MEEL-yə (English), ah-ME-lyah (Italian), ah-ME-lee-ah (German)	English, Spanish, Italian, Polish, Dutch, German, Ancient Germanic
Jacqueline	zha-kə-LEEN (French), zhak-LEEN (French), JAK-ə-leen (English), JAK-ə-lin (English)	French, English
Sung-Jin	sung-jeen	Korean