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- prove mettle
prove mettle
prove your mettle
(slightly formal) also show your mettle to show that you are brave and have a strong character As a reporter, she certainly proved her mettle working in the midst of a war zone.
prove/show your mettle
(slightly formal) to prove that you are good at doing something by succeeding in a difficult situation A relative newcomer to the game, he's certainly proved his mettle in the last two games.