As 2OII drew to an end, Turkey took major steps in the ongoing race between rival pipeline projects that seek to supply natural gas to European markets. It first signed a memorandum of understanding with Azerbaijan for the construction of the Trans-Anatolia pipeline that will carry Azerbaijani natural gas to Europe through its territory and means an additional line for its imports from Azerbaijan. Though this unexpected development might thwart specific pipeline projects such as Nabucco, supported by European energy companies, overall, the joint Azerbaijani-Turkish project is likely to contribute to the southern corridor promoted by the EU as a way to bolster its energy security by building alternative natural gas pipelines from the Caspian basin. Only a few days later, Turkey, in an unexpected move, reached an agreement with Russia that will allow the construction of part of Gazprom's ambitious South Stream pipeline in Turkey's territorial waters in the Black Sea. South Stream aims to consolidate Gazprom's dominant position in the European markets and is seen as Gazprom's most lethal weapon to forestall competition from EU-backed projects - and is therefore a rival.In the iggos, in contrast, Turkey largely positioned itself against Russia, when arguably the new great game over the development and transportation of the Caspian basin and central Asian reserves was about to start. Having coordinated its energy policies with the east-west corridor supported by the western powers, Turkey took an active role in projects that aimed to bypass Russian-controlled transportation lines and bolster the economic and political independence of the new states in the region. The rivalry among various oil-and-gas pipelines advocated by the United States and EU on the one hand and Russia on the other continued throughout the last decade. Turkey remained committed to projects backed by western powers but increasingly developed a more cooperative relationship with Russia's rival projects; it also rendered itself dependent on Moscow for its soaring energy needs.The multifaceted energy relations between Turkey and Russia offer a crucial case to study the changing priorities of Turkish foreign policy and the limits of this transformation. Turkey has adopted cooperative policies based on positive-sum logic and downplayed competitive negative-sum calculations. With this new approach to international relations, Turkey seeks to use interdependencies forged through economic exchanges as a tool to dampen political disputes and induce positive transformation in the behaviour of its partners. The transformation of Turkish- Russian relations from adversity to managed competition and the current phase of multidimensional partnership owes a great deal to the economic interdependence imparted most crucially by energy cooperation. Turkey's pursuit of a more independent approach vis-a-vis the west and its forging of closer economic and political relations with its northern neighbour Russia are a testament to the success of its new foreign policy vision, which also values cooperation with its immediate neighbours. As this article will argue, Russia's failure to deliver on Turkey's expectations in both energy and neighbourhood issues exposes the limitations of this new approach. The return to competitive dynamics after the parties reached a historic grand bargain in energy cooperation in 2009 clearly reveals the boundaries of Turkey's positive-sum approach to energy cooperation with Russia.DYNAMICS OF TURKISH-RUSSIAN ENERGY RELATIONS: BETWEEN RIVALRY AND DEPENDENCEEnergy relations between Russia and Turkey exhibit interesting patterns, reflecting Turkey's various roles in energy markets. In recent years, Turkey's energy policies have been based on two interrelated roles as a consumer and as a transportation corridor aspirant. First, since it is a net importer of hydrocarbons, which form a disproportionally major share of its energy mix, Turkey is under constant pressure to ensure access to reliable energy sources at affordable costs. …