The quantization problems of the gluon fields are investigated in the lightcone gauge, n(mu)A(mu)(a)(x) = 0, where n(2) = 0. In this gauge, the gluon propagator has unphysical poles of kind 1/(nk). In order to remove these singularities, Leibbrandt and Mandelstam have proposed a new prescription. In this work we introduced a new modified lightcone gauge, which is (n(mu) + i epsilon/(n*k)k(2)k(mu))A(mu)(a) = 0 where n(mu)(*) is the dual vector to n(mu). We proved that Leibbrandt-Mandelstam prescription can be obtained on the basis of consistent quantization. The Ward identity in the modified lightcone gauge was also investigated. (C) 2001 Published by Elsevier Science B.V.