The historical record of great power transitions is plagued with episodes of violence. Hence, the ‘rise of China’ and America’s relative decline sparks a heated debate on whether history, in the longer or shorter term, will repeat itself. The possible outcomes of this cyclical event, ranging from hegemonic war to a smooth transition, vary with the theoretical approach adopted: power transition theory postulates that the rising challenger becomes more conflict-prone as it approaches the crossover point with the declining hegemon in terms of power, while liberal-institutionalist theory draws attention to the exceptional character of the current Western-led order as the main cause for optimism. In this comparative analysis, each theory’s conflicting concepts of power, and the contrasting expectations each hold for transitions, are compared. Their focus on different indicators in measuring power yields different answers about the size of the US-China power gap and the speed at which it is being closed; at the same time, opposing assumptions on state satisfaction influence the hypothesis of China being successfully accommodated by the international system. An empirical analysis focused on the rising challenger’s behaviour over the past two decades reveals alternating periods of revisionism and status quo orientation, but in the recent past liberal-institutionalist theory is more apt for understanding China’s posture vis-à-vis the US, even after discounting for uncertainty and calculative behaviour. On the US’ suppositional impulse to seek confrontation in a desperate attempt to retain its leading position in the system, evidence on its approach to China also dismisses the alternative proposition of preventive action suggested by power transition theorists.