Despite the extensive studies in the field of diffusion, the role of innovativeness in diffusion models has not reached a consensus and the literature has dedicated little effort to modelling customers' heterogeneous opinion leadership. These gaps could be some of the key limits for the further exploration of the diffusion phenomena. This study proposes that the use of innovativeness in diffusion models can be seen as a filter for potential customers and as an indicator for customers' opinion leadership. We analyse the respective roles of innovativeness and opinion leadership in diffusion based on the suggested model. We also show the model's potential to identify and predict the opinion leaders of a diffusion system. We implement the proposed model in the case of a 3G mobile phone technology. The results demonstrate good fitting and forecasting performance of the model. We hope the insights offered by this study can benefit both innovation academics and practitioners.