  We demonstrate that stability of r-modes in young rapidly rotating pulsars
might be explained if one takes into account strong medium modifications of the
nucleon-nucleon interaction because of the softening of pionic degrees of
freedom in dense nucleon matter. Presence of the efficient direct Urca
processes is not required. Within our model the most rapidly rotating observed
young pulsar PSR J0537-6910 should have the mass $\geq 1.8M_{\odot}$.
