Results of molecular simulations are presented for the entropy-driven collapse of a single chain in an athermal solvent. The mean square radius of gyration ([R(g)(2)]) is calculated for a flexible chain of length N immersed in a hard-sphere medium having a specified solvent chemical potential. For a ratio of chain bead diameter to solvent diameter of 0.2 and packing fraction eta = 0.44, we find that [R(g)(2)] proportional to N-2 nu with nu-0.36 for N greater than or equal to 100; such exponent is consistent with that predicted by and density on [R(g)(2)] are consistent with the predictions of the Edwards-Muthukumar theory for a chain in a quenched, random medium.