set back on one's heels v. phr.,
informal To give an unpleasant surprise; upset suddenly; stop or turn back (someone's) progress.
Jack brags too much and it set him back on his heels when the coach told him he wasn't as good a player as he thought he was. Jean was doing very well in school until sickness knocked her back on her heels. Compare: KNOCK FOR A LOOP, THROW FOR A LOSS.
[TahlilGaran] English Idioms Dictionary ▲