This paper focuses on the effects of cross-linguistic phonological and semantic similarity on the lexicon of late unbalanced bilinguals. Using Russian words as masked primes and English words as targets, the expectation is that primes and targets overlap phonologically, semantically, both phonologically and semantically, or do not overlap at all. Participants in the experiment were asked to keep the targets in memory and match them against occasionally presented stimuli. N170 and N400 components of the word-elicited high-density ERPs were identified and assessed in signal and source space. Results highlighted that the reaction times were shorter in case of cross-linguistic semantic similarity. The semantics-related N400 amplitude difference correlated with individual L2 proficiency. On the other hand, phonological similarity suppressed the N400 amplitude in the semantically unrelated condition. Cortical generators in the left IFG and the temporal pole appear to be at the basis of these ERP dynamics.