As the traditional teaching paradigm is reversed in Flipped Classroom Model (FCM), it has the potential to empower the teacher to allocate more valuable face-to-face classroom time for productive language tasks. Digital flipped course contents encourage the students and the teacher to take advantage of becoming a member in an online learning community and engage in a social-constructive learning approach. Such a profound shift from the traditional teaching and learning paradigm may influence the identity progression of L2 teachers. This longitudinal study aims to explore the ramifications of flipped grammar teaching on four L2 teachers' identity progression over the course of two academic years within the three fundamental modes of belonging for identity formation, namely engagement, alignment, and imagination, identified by Wenger (1999) at tertiary level. Methodological triangulation was adopted to boost the transferability and reliability of the findings. Semi-structured interviews provided in-depth insights into the four L2 teachers' relational thinking about flipped grammar teaching and their professional identity progression. The data also included four hours of classroom observations to witness the real-life implications of teachers' accounts. The twofold data was analyzed using deductive content analysis. The results indicated that English teachers need to make long lasting and conscious efforts towards a reconciliation between their existing identities and FCM. The teachers not only need to find accommodation strategies to ensure better integration of reluctant students into FCM but also overcome their own accuracy-based exam anxiety as they redefine their grammar identities incorporating FCM.