ma·no a ma·no

/ˌmɑːnoʊɑˈmɑːnoʊ/ adv

— used to describe a situation in which two people directly compete, fight, or argue with each other

They fought mano a mano.

Tomorrow night the candidates (will) go mano a mano [=compete against each other] in the first of two debates.

◇ Mano a mano comes from a Spanish phrase that means “hand to hand.”