catch off guard

catch (one) off (one's) guard

To engage, take advantage of, or seize upon one when one is not especially careful, vigilant, or prepared for danger or surprises. He's got a lot of tricky moves, so make sure he doesn't catch you off your guard! The soldiers moved in quickly, hoping to catch the enemy troops off their guard. I think I caught him off his guard when I told him I was resigning.
See also: catch, guard, off

catch (one) off guard

To engage, take advantage of, or seize upon one when one is not especially careful, vigilant, or prepared for danger or surprises. He's got a lot of tricky moves, so make sure he doesn't catch you off guard! The soldiers moved in quickly, hoping to catch the enemy troops off guard. I think I caught him off guard when I told him I was resigning.
See also: catch, guard, off
Farlex Dictionary of Idioms.

catch someone off guard

 and catch one off (one's) guard
Fig. to catch a person at a time of carelessness. Tom caught Ann off guard and frightened her. She caught me off my guard, and my hesitation told her I was lying.
See also: catch, guard, off
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

catch off guard

see under off guard.
See also: catch, guard, off
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • 1FTR
  • drive (one) out of office
  • force (one) out of office
  • force out of office
  • give (one) (one's) head
  • give head
  • give somebody their head
  • give someone their head
  • deep water
  • cooking for one