From Longman Dictionary of Contemporary Englisheyeball to eyeballeyeball to eyeballLOOK ATif two people are eyeball to eyeball, they are directly facing each other, especially in an angry or threatening way → eyeball
Examples from the Corpus
eyeball to eyeball• It walked around a bit and stared at me through the glass, eyeball to eyeball.• You never knew if you were going to come eyeball to eyeball with somebody right then. 