Learning a new word involves integration with existing lexical knowledge. Previous work has shown that sleep-dependent memory consolidation processes are important for the engagement of novel items in lexical competition. We used spaced learning and testing to investigate memory for novel words and their lexicalization across the course of a single day, compared with a day later. We expected that the benefits of spaced learning would enhance knowledge of the novel words, and may provide the interleaving of new and old information that allows lexicalization to occur. The degree to which a new word engaged in lexical competition with phonological neighbors was employed as a marker for lexicalization. We found evidence for enhancements in memory performance following a time period including sleep, but we also found lexical competition effects emerging within a single day. This suggests that while sleep-dependent memory consolidation may be sufficient for lexicalization, it is not a necessary pre-condition.