Illustration depicting the possible evolutionary paths of a chemically homogeneous star with initial mass ≳ 20 M_⊙ at SMC metallicity. After core H-burning (yellow ball with blue center), the star contracts, Γ_e,switch decreases and Γ_e increases. If Γ_e > Γ_e,switch the star enters the optically thick winds regime (left arrow) and ends up being a WR (channel 1). If Γ_e < Γ_e,switch (right arrow), winds are still optically thin during shell H-burning (yellow ball with blue shell) and the star expands and cools, increasing Γ_e,switch. At this stage, there are two possible outcomes: (i) If the star cools enough to cross the bi-stability jump T_eff < 25 kK (right arrow), it may enter the optically thick wind regime and become a WR (channel 2). (ii) If the star starts core He-burning at T_eff > 25 kK (left arrow), T_eff rises again, and the star does not cross the bi-stability jump. Optically thick winds are not activated (or are activated too late) and the star ends up being a cool supergiant.