To take up the gauntlet / To accept the challenge
Literally 'to pick up the glove'. Means accepting a challenge or invitation to compete. From the medieval tradition of throwing down a glove as a challenge.
They threw down the challenge and he took up the gauntlet without hesitation.
—Do you accept? —I take up the gauntlet. We'll see who wins.
Nobody dared take up the gauntlet except her.