Interprofessional collaboration is essential for achieving the quintuple aim in patient care: enhancing outcomes, improving patient experience, reducing costs, supporting provider well-being, and advancing health equity. The successful translation of collaborative care models into practice requires deliberate implementation strategies. Champions are key agents of change in the implementation of interprofessional collaborative care. However, despite available implementation recommendations, a deeper understanding of the factors influencing the change process is needed. This study explored how TeamSTEPPS Master Trainers (MTs) at Geneva University Hospitals adopted and enacted their champion role and examines the factors that shaped their experiences. We conducted semi-structured interviews with 14 MTs (physicians, nurses, and physiotherapists), recruited through purposive sampling. Transcripts were analyzed thematically at individual, relational, and institutional levels. Our results highlight that champions were strongly motivated and valued the opportunity to strengthen teamwork. Their active commitment and open communication facilitated implementation, whereas staff resistance, mistrust, and high turnover were significant challenges. Although initial training was beneficial, participants highlighted the need for ongoing support and contextual adaptation. Institutional recognition and communities of practice enhanced legitimacy. In conclusion, champions are essential in advancing interprofessional collaboration, but their impact depends on broader organizational conditions. Sustained change requires participative implementation, leadership support, and mechanisms for collective learning.