Recently, we have observed, using molecular simulation, a premelting transition at the Al(s)/Pb(l) solid-liquid interface. Here we examine the effect of the premelting layer on the spreading of Pb(l) droplets on an Al(s) substrate. Premelting only is seen to occur at the Al-Pb solid-liquid interface, but not at the Al(s) solid-vapor interface. Thus, the spreading of the liquid droplet is accompanied by a corresponding melting of the underlying Al surface. In this respect, the spreading is similar to that of a droplet exhibiting reactive wetting. The presence of the premelting layer enhances the wetting of the droplet, that is, the equilibrium wetting angle for the droplet on the surface premelt is significantly smaller than that for a droplet spreading on a surface for which premelting is artificially hindered. We also show that the presence of the premelting layer has a significant effect on the spreading kinetics and mechanism.