When the auditory information is deteriorated by noise in a conversation, watching the face of a speaker enhances speech intelligibility. Recent findings indicate that decoding the facial movements of a speaker accelerates word recognition. The objective of this study was to provide evidence that the mere presentation of the first two phonemes--that is, the articulatory gestures of the initial syllable--is enough visual information to activate a lexical unit and initiate the lexical access process. We used a priming paradigm combined with a lexical decision task. The primes were syllables that either shared the initial syllable with an auditory target or not. In Experiment 1, the primes were displayed in audiovisual, auditory-only or visual-only conditions. There was a priming effect in all conditions. Experiment 2 investigated the locus (prelexical vs. lexical or postlexical) of the facilitation effect observed in the visual-only condition by manipulating the target's word frequency. The facilitation produced by the visual prime was significant for low-frequency words but not for high-frequency words, indicating that the locus of the effect is not prelexical. This suggests that visual speech mostly contributes to the word recognition process when lexical access is difficult.