We show that Pb nanowires may grow by co-sputtering of Al-Pb target. During sputter deposition, stress is generated inside the deposited film. Because Pb is immiscible in Al, stress relaxation occurs through Pb segregation along the aluminum grain boundary. Extrusion of Pb is inhibited if a few layers of Al oxide are formed on the surface of the film. However, if the surface oxide is broken by external perturbations, for example air-operated corrosion or electron beam, then segregated Pb extrudes in form of nanowires.