As a benefit of modularization of complex systems, Original Equipment Manufacturers (OEMs) can choose suppliers in a less constricted way when faced with new or evolving requirements. Before a supplier is selected for each module, a group of potential suppliers should be identified in order to control the uncertainty along with other performance measures of the new system development. In modular design, because suppliers are more involved in system development, the potential supplier identification should be combined with potential architecture identification to manage uncertainty as well as requirements satisfaction level by potential suppliers. In this paper, we propose an Architecture & Supplier Identification Tool (ASIT), which generates all possible architectures and corresponding suppliers based on new requirements through matrix-mapping and propagation. Using ASIT, the overall uncertainty and requirements satisfaction of generated architectures can be estimated. The proposed method aims at providing decision support for the early design stage and thereby helping companies to have an integrated view of suppliers and system architectures to better satisfy customer requirements and reduce risk.