Previous research investigating the dynamical processes supporting coordinated joint action has typically used non-goal-directed tasks. The present study expands on this research by investigating the coordination that emerges among pairs in a complex, goal-directed task of herding virtual sheep to the center of a field. The results revealed that the majority of pairs converged on the same stable movement coordination strategy in order to complete the task. This strategy involved pairs moving in an in-phase or anti-phase oscillatory pattern around the sheep. By adopting this strategy pairs formed an interpersonal synergy. Interestingly, the strength of this synergy was modulated by the number of sheep being herded. More specifically, more dimensional compression was observed among pairs when herding the 7-sheep compared to herding 3 or 5 sheep. The implications of these results for understanding how task difficulty and mutually defined environmental co-regulation influenced the behavioral dynamics of coordinated joint-action are discussed.