set you back on your heels

set (one) back on (one's) heels

To put one into a state of surprise, unease, or bemusement, especially such that it affects their ability to perform or function. The sudden arrest of one of our teammates last night certainly set us back on our heels, and we weren't able to play to the best of our abilities this morning. The tragedy set the entire community back on their heels.
See also: back, heel, on, set
Farlex Dictionary of Idioms.

set you back on your heels

or

rock you back on your heels

If something sets you back on your heels or rocks you back on your heels, it surprises or shocks you. Something very odd occurred, and it set me back on my heels. Ireland started well, only to be rocked back on their heels by the first error just 10 minutes into the match.
See also: back, heel, on, set
Collins COBUILD Idioms Dictionary, 3rd ed.
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
  • cooking for one
  • as one door closes, another (one) opens