Emerging powers have tried to build functional regional power bases in their respective spheres of influence to gain support for their leadership projects and representative capacities on the global stage. This has caused diverse contestational responses by secondary powers in different regional orders. In this context, we analyse the shift of Colombia's contestation approach towards the Brazilian leadership claim in South America. With the arrival of President Santos, Colombia turned from collateral hard balancing against Brazil to institutional contestation through the Pacific Alliance. Besides furnishing evidence of the broader Colombian soft-balancing strategy in other policy areas, the article explores and balances the domestic, structural and behavioural drivers of the strategic turn to institutional contestation through the Pacific Alliance without neglecting the economic and political motives of Colombia's engagement in the pro-market alliance.Keywords: Brazil, collateral hard balancing, Colombia, foreign policy strategies, institutional contestation, Pacific Alliance.Since the end of Cold War, there has been increasing discussion of the future features of an increasingly multipolar world. A great deal of attention has been paid to the emerging powers and the strategies they are using in their respective spheres of influence to obtain acceptance of their leadership claims and their representative capacities at the global level. While new powers like Brazil and the other states from the Brazil, Russia, India, China and South Africa coalition (BRICS) have gained acceptance at the global level, they often face regional contestation. As no state considers itself a pure follower of another state, each secondary regional power generally tends to project different types and degrees of contestation to the primary power's leadership claim in its region in order to preserve its autonomy and self-determination.Conflicts over the assertion of regional leadership will impact the future world order because their results will determine whether new global powers will be able to project influence from a functional regional power base or they will be busy managing regional conflicts. There is a growing literature discussing the strategies of secondary powers towards regional powers. Critics of the contestation approach are right in arguing that