on your mettle
ready to do something as well as you can in a difficult situation:
Both players were on their mettle in the final round.
Cooking for such important people really puts you on your mettle.

[TahlilGaran] Advanced Learner's Dictionary ▲

on your mettle
if you are on your mettle, you are ready to try as hard as possible because your abilities are being tested
be on your mettle
to be determined to prove that you are good at something, especially in a difficult situation

[TahlilGaran] English Idioms Dictionary ▲