This corpus-based paper investigates the frequency, grammatical irregularity, and variational behaviour of formulaic sequences consisting of the N1 to N1 pattern with body-part nouns (e.g. face to face) and the analogical extension of the pattern to new, less frequent body-part nouns. These phrases show signs of lexicalization, such as lack of singular/plural distinction, lack of articles and very low likelihood of adjective insertion. While the pattern itself is grammatically irregular, it has a tendency to go through the regular process of conversion from an adverbial (go head to head), via a premodifier (a head-to-head competition) to a noun (a Christie-Lewis head-to-head). One further sign of univerbation is the use of hyphens, which is most frequent in the premodifier function and in nouns.