Teacher-student relationships (TSRs) are key factors for at-risk students. However, little is known regarding how TSRs are built through interactions with students with neurodevelopmental disorders (NDDs). This study provides an in-depth analysis of a teacher's relational competence in relation to a student with NDD symptoms. We used microscopic relational analysis to scrutinise a TSR, focusing on a brief classroom episode selected from a sample of seven video-recorded lessons set in an elementary school. Our findings demonstrate the critical role of teachers' relational competence in nurturing positive and supportive TSRs. Teachers' relational competence manifests through continuously reading, understanding, and empathising with students. Furthermore, teachers can promote mutual understanding and respect, regulate the degree of closeness and distance, and manage the emotional indicators of ongoing TSR. We propose that such microsocial artistry is an essential part of teachers' competencies when interacting with students with NDDs.