In the Tianjin dialect, casual utterance of familiar trisyllabic sequences often induces deletion of phonological segments so that for a trisyllabic string, the non-final syllables would merge into a single syllable. This elide-and-merge process interacts with the rich Tianjin tone sandhi system to produce rather complicated patterns. In this paper, casual speech elision is shown to fall out straightforwardly from a model that recognizes morae as associated with segments and also as tone-bearing units. Thus, elision of morae also removes tonal features. While this understanding provides a clear description of the patterns, it also reveals an ordering paradox: sandhi applies before elision in some cases, but after elision in others. The paradox is resolved by favoring the order that produces a contour tone for the merged syllable. An explanation for this can be found if one recognizes that Tianjin is prosodically iambic.