As they sit at the nexus of where internal and external organizational interests meet and must be reconciled, purchasing and supply chain managers assume a key boundary mediation role. In this respect, their ability to influence supplier representatives is a sine qua non of successful supply chain management. This article investigates influence tactics of a subtle character, specifically, how managers from a buying organization (influence agents) manipulate supplier representatives’ (influence targets) behaviors by involving a third person. So far, this phenomenon has received only scarce attention as existing literature on social influence in buyer-supplier relationships tends to (i) adopt an organizational-level unit of analysis, and (ii) if examining the individual-level seldom extend beyond a dyadic perspective. Drawing on Social Control Theory and employing an exploratory case study with data collected over a two-year period, the author identifies seven distinct influence tactics involving a third person and develops an overview of antecedents motivating their use. With these findings, this article makes a novel theoretical contribution by developing a deeper understanding of underexposed social influence dynamics in individual-level triads in buyer- supplier relationships.