We present a Monte Carlo study of the structure of an entangled polymer melt confined between parallel plates separated by a distance smaller than the radius of gyration R-g of the chains. Within that regime, we find a dramatic increase in the molecular weight between entanglements and in the eigenvalues of the gyration tensor of the chains in the plane of the plates. The chains however appear to retain their Gaussian behavior throughout confinement. Interestingly, we also observe that individual chains at short length scales form "globules" whose density and size increase with the extent of confinement. (C) 2011 Elsevier Ltd. All rights reserved.