Research SummaryCollaboration among employees is the bedrock of an organization, but we suggest that it can be undermined by their extra‐organizational affiliations. We point to the hidden but common constellation of two coworkers who are also affiliated with organizations that compete with one another. We hypothesize that such colleagues collaborate less with one another when performing on behalf of their shared employer. Using data from professional soccer, we provide empirical evidence. We outline implications for research on extra‐organizational affiliations, intraorganizational collaboration, competition and rivalry, and social networks.Managerial SummaryImagine two soccer players who play for the same soccer club – but compete against one another when they perform on behalf of their national team (i.e., the two players have different nationalities). We show that the two soccer players collaborate less (i.e., play fewer passes to each other) at their club after encountering each other as opponents when performing on behalf of their national teams. This finding in the context of sports has implications for firms. Managers of the same firm may serve on boards of directors of companies that compete with each other, and employees may support political parties that compete – eventually hindering internal collaboration.