Abstract: With the globalization of supply chains and the rapid changes in the business environment, how to deal with supply risks is one of the core issues that need to be considered in the operation management of enterprises. Considering the upstream disruption risk, we investigate a co-opetition problem in which an original equipment manufacturer (OEM) can replenish components from his rival, the integrated device manufacturer (IDM), after the random disruption of the OEM's supplier is realized. The IDM is perfectly reliable. We observe that, under the premise that the upstream supplier obtains the order and the supply is disrupted, the replenishment cooperation between the two manufacturers will be reached. However, from the holistic perspective, depending on the market potential, supply reliability, product substitution, and cost, the competition and cooperation between the two manufacturers may coexist or be mutually exclusive. In addition, it is different from the results of the previous literature: the existence of backup replenishment option for downstream company reduces the order quantity obtained by the (upstream) supplier with supply risk. After introducing competition and cooperation, we find that the existence of replenishment cooperation option can increase the order quantity obtained by the upstream supplier with supply risk; that is, the cooperation between the two manufacturers has an upward spillover effect. Furthermore, we find that the cooperation increases the total quantity of products put on the market by the two manufacturers; that is, the replenishment cooperation between the two competing manufacturers also has a downward spillover effect: reduce market prices and increase consumer surplus.