This article examines how one first-year physics teacher translated his inquiry-based, socially just pre-professional learning into classroom practice in his first several months of teaching, using rhizomatics, a non-linear theory of social activity, as a theoretical and methodological frame. This case highlights the complexity of enacting a social justice-oriented pedagogical practice as a new teacher in a constrained school environment. Although the participant experienced positive interactions with his students, he faced multiple external challenges as well as his own internal conflicts about teaching methods. These conditions influenced him to adopt more traditional practices than those that were espoused in the participant's teacher education programme, although some evidence of progressive teaching surfaced inconsistently. Authors provide recommendations for teacher educators and policy makers to better support new teachers as they transition into the first year of teaching, and call on researchers to explore methodologies and theories that can account for nonlinearity, complexity and multiplicity in investigating teaching and learning.