Digital marketing has received much attention from most firms recently, and with the increasing competition and exigency, marketing managers’ need for reliable and scientifically supported decision systems to assist them has never been greater. This paper presents a management model for estimating the quantity of online leads they should generate in a given period of time in order to achieve their goal, measured in contracts gained, in the most effective and efficient way possible. Through the application of Game Theory, the strategies of the rival firms are taken into account to provide marketing managers with a set of reliable possible decisions that can bring the firms competitive advantage. The applicability of the model is tested through two different scenarios, comparing the results with the actual data, and reaching the conclusion of the great potential that the proposed model evidences. Through the using of the model, the firms are able to benefit from it by operating at a more efficient level and by saving costs from the online lead generation and digital marketing budget.