Complex network analysis is applied to study late second language (L2) acquisition using highly proficient late L2 learners when compared to monolinguals performing a morphosyntactic task. Specifically, we assess for (dis)similar topological properties of the functional networks associated with a gender mismatch condition between article and noun at the beginning of a sentence in a Spanish monolingual group and a group of late learners of Spanish whose native language is English (which does not encode gender as a grammatical category). Our results suggest that the detection of incorrect grammatical gender agreement in Spanish recruits the neural networks that subserve the cognitive processing differently in each group. This result provides insight into the functional cooperation and interactions of brain areas while processing an L2 trait not present in L1.