Blending is generally seen as a marginal source of linguistic innovations in language change. However, the im-pact of blending is likely underestimated, because blends may occur under the guise of analogical extension. In such cases, blending is covert and cannot be detected synchronically in the innovative structure. In this paper, the relation between analogy and blending is analyzed. Next, the role of covert blending is demonstrated in two diachronic case studies. The first case study addresses the use of the English verbs want and need in the Passival Participle Construction (e.g. you need your eyes testing). The pattern could have analogically extended from perception verbs, as claimed by Visser (1963-73), but distributional, chronological and semantic evidence indi-cate that the extension happened through blending between two other constructions, the Passival Gerund Con-struction (your eyes need testing) and the Object Complement Construction (you need your eyes tested). The second case study deals with the development of the Dutch downtoner allesbehalve ('not at all'). It is shown that once allesbehalve had adopted the syntactic status of a downtoner it spread to new syntactic contexts. Since this brings allesbehalve in line with other downtoners, the process can be seen as an instance of analogical extension. Quantitative evidence, however, shows that the developing syntactic behaviour of the downtoner continues to be influenced by the syntax of its composing elements, alles ('everything') and behalve ('except'). Change is thus partly driven by blending between the downtoner and its own historical source. In both cases, apparent analogical extensions hide an underlying blend. These findings show that blending may be more pervasive than generally recognized, supplementing rule-based strategies for coining new utterances.