It depends on your mental hierarchy doesn't it? It's easy enough to see lexing as a sub-step of parsing. It's also quite arguable that the classical emphasis of a separation between parsing and lexing is as much an artifact of classical tools than a "natural need".

For instance, from a Chomsky's hierarchy of languages perspective lexing and parsing are simply language analysis at two different levels on the hierarchy with lexing focused on the "regular" language embedded within a larger context-free or context-sensitive language.