Organisations are expected to possess the ability to adapt in order to sustain themselves in the ever-changing markets. Routines, which have traditionally been viewed as a source of stability, have recently been conceptualised as a source for organisational flexibility, having the capability to significantly determine whether an organisation can survive. This study contributes to this discussion by showing that the internal dynamics of routines, which comprise of ostensive and performative aspects, play a significant role in the emergence of endogenous routine flexibility. Insights into the ostensive-to-performative relationship have been gathered by studying a temporary project team over 18 months. Specifically, there are three insights: (1) routine actors’ pursuit to embrace the tacitness of routines promotes the emergence of ostensive routine change that is temporarily disengaged from the performative aspect, (2) the emergence of options at the ostensive level, act as a mechanism to legitimise the performative aspect, and (3) decoupling forms a mechanism for performative flexibility to accommodate the changing ostensives in the form of targeted outcomes. These insights lead to further understanding of the different types of relationships that exist within the internal dynamics of a routine i.e. disengaged, legitimation, and accommodating relationship. These ostensive-to-performative relationships exist due to the collective effort of the temporary team.