Research on interpersonal synchronization deals with the coordination of behavior, cognition and affect within interacting individuals. The phenomenon of synchronization has been explored in many settings and numerous definitions have emerged. The purpose of this study was to compare nonverbal synchrony (based on overall body movement) with the concept of complementarity (based on interpersonal theory) in a competitive context. We examined 40 previously unacquainted same-sex dyads (21 female, 19 male; mean age = 22.81). Dyads underwent a 15-min videotaped competitive role-play. Nonverbal synchrony was quantified by a frame-differencing method, and complementarity by a joystick tracking method. Results revealed that dyads behaved in a synchronous and complementary manner. We found that nonverbal synchrony was positively correlated with affiliation complementarity, but not dominance complementarity. The present study compared nonverbal synchrony with complementarity. The link between the two concepts was small, as indicated by rather weak correlations between nonverbal synchrony and affiliation complementarity. Our results reinforce the view that competitive behavior depends on complex dyadic interactions, including nonverbal and verbal behavior.