A turbomachine combustor portion includes a combustion chamber. A center injection nozzle is arranged within the combustion chamber and includes a center nozzle inlet and a center nozzle outlet. An outer premixed injection nozzle is positioned radially outward of the center injection nozzle and includes an outer nozzle inlet and an outer nozzle outlet that is arranged upstream of the center nozzle outlet. A late lean injector is positioned downstream of the center nozzle and the outer premixed nozzle. The combustor portion includes a first combustion zone arranged downstream of the outer nozzle outlet, a second combustion zone arranged downstream of the center nozzle outlet, and a third combustion zone arranged further downstream of the center nozzle outlet. The center injection nozzle, outer premixed injection nozzle, and late lean injector are selectively operated to establish a combustion flame front in the first, second, and third combustion zones.