μονομᾰχ-έω · monomach-eō — LSJ
fight in single combat, E. Ph. 1220; τινι with one, Hdt. 9.26, Pl. Cra. 391e, etc.; πρός τινα Plb. 35.5.1.
μοῦνοι Ἑλλήνων μουνομαχήσαντες τῷ Πέρσῃ having fought single-handed with the Persians, of the Athenians at Marathon, Hdt. 9.27; δυοῖσι οὐκ ἂν μουνομαχέοιμι Id. 7.104.
fight as a gladiator, Posidipp. 22, Luc. Tox. 58, Hdn. 1.17.2, D.C. 75.16.