Inversionless gain in a degenerate three-level system driven by a strong exteal field and by collisions with a buffergas is investigated. The mechanism of population distribution in upper laser level, contributed by the collision transfer,as well as by relaxation, induced by pressure of a buffer gas, is discussed in detail. Explicit formulae for analysis ofoptimal conditions are derived. The idea developed here for the incoherent pump could be generalized to other systems.