This study aimed at characterizing the cognitive processes that come into play during speech-in-speech comprehension by examining lexical competitions between target speech and concurrent multi-talker babble. We investigated the effects of number of simultaneous talkers (2, 4, 6 or 8) and of the token frequency of the words that compose the babble (high or low) on lexical decision to target words. Results revealed a decrease in performance as measured by reaction times to targets with increasing number of concurrent talkers. Crucially, the frequency of words in the babble significantly affected performance: high-frequency babble interfered more strongly (by lengthening reaction times) with word recognition than low-frequency babble. This informational masking was particularly salient when only two talkers were present in the babble due to the availability of identifiable lexical items from the background. Our findings suggest that speech comprehension in multi-talker babble can trigger competitions at the lexical level between target and background. They further highlight the importance of investigating speech-in-speech comprehension situations as they may provide crucial information on interactive and competitive mechanisms that occur in real-time during word recognition.