The expansion of globalising cities into global city-regions poses fundamental questions about how best to govern the new metropolis. Partly because of the relentless pace of change, these newly emerging metropolitan spaces are often reliant on inadequate urban-economic infrastructure and fragmented urban-regional planning and governance arrangements. Moreover, as the demand for more 'appropriate', widely understood to mean more flexible, networked and smart, forms of planning and governance increases, new expressions of territorial cooperation and conflict are emerging around issues of increased competitiveness, infrastructure development, the collective provision of services, and further governmentalised remapping(s) of state space. We identify four central tenets of the metropolitan region/governance debate and discuss their relevance for future research on city-regions: (1) periodisation and trajectories, (2) democracy and accountability, (3) form and function, and (4) fragility and mobilisation. These, we argue, pose key challenges for rethinking city-region governance within the emerging new metropolitan paradigm.