While is widely accepted the dynamic nature of value creation in business relationships, most of the research presents cross-sectional and dyadic approaches. This research takes a more dynamic approach by examining how and why a buyer-firm transfers orders from a supplier to another in a strategic sourcing context through a certain period of time. We explore the managerial situation of two suppliers competing for the buyer preference, and the process of buyer’s choice between two suppliers in search of higher value creation and appropriation. We analyze six cases of strategic sourcing, each one formed by a triad (two dyads linked by a common buyer), in a longitudinal-retrospective approach. Integrating two different streams of value creation theories (industrial marketing and strategic management), and dynamic capabilities theory, we propose a conceptual model that includes both buyer’s and supplier’s perspectives of value creation and appropriation. According to the model, there are four consecutive stages of value creation in a strategic sourcing context. Buyer-firms choose the most suitable stage of value creation for a given strategic sourcing according to the degree of uncertainty in the business environment, its internal demands and business opportunities. The chosen supplier will be the one that has the attributes to transact at this stage of value creation. On the other hand, supplier-firms seek to establish business relationships with buyer-firms that enable them to expand sales, thanks mainly to the reputation of being a supplier of an exigent customer. Moving to superior stages of value creation can lead to a higher value appropriation and, eventually, to competitive advantage. However, this movement requires investments of the parties to strengthen operational capabilities and developing dynamic capabilities. We shed light on the tradeoffs faced by purchasing managers in their search for competitive advantage, as well as the contingent factors present in strategic sourcing. The model may guide purchasing and sales managers in finding the most suitable stage of value creation to strategic sourcing relationships, according to their level of environmental uncertainty, internal needs, and investment capacity.