IDIOMS

put up one's dukes

(idiomatic, by extension) To take firm action or to show oneself to be committed to such action, as when competing in a sporting event or other contest.

Example: 1886, Edward Money, The Truth about America[1], page 206:
  The proceedings of the State Democratic Convention, held at Turner Hall, yesterday, were disgraceful enough to bring a blush even to the cheek of a Democrat. "Liar," "snide," "put up your dukes, if you want to fight," catcalls, hooting, and yelling filled up a greater part of the deliberations of the august body.
2008, Jonathan Schaeffer, One Jump Ahead: Computer perfection at checkers[2], ISBN 9780387765754, page 401:
  The NBC reporter who came to the match on Wednesday told Lafferty "Come on, put up your dukes, we want to see some blood."