A water film squeezed between a hydrophobic solid (S) and a polymer melt (P) is metastable and dewets by nucleation and growth of a dry patch (radius R(t) at time t) surrounded by a rim (collecting the rejected water). Taking into account the viscoelastic behaviour of P, we are led to predict : a) a pure elastic regime if R < Rc, where the melt behaves like a rubber, with R(t) ∼t3/4 ; b) a viscous regime, at longer times, where the rim is extended by its friction against P, and moves at constant velocity.