An improved gas turbine combustor of the type including primary and secondary combustion chambers with a venturi including a throat portion located therebetween; a plurality of primary fuel injection nozzles secured to a combustor cap in an annular array upstream of the primary combustion chamber; and a centerbody including a secondary fuel nozzle, said centerbody extending from said combustor cap to said secondary combustion chamber; the improvement comprising a plurality of tertiary fuel injection nozzles arranged in a circular array about a longitudinal axis of the combustor, at a location downstream of said venturi throat portion, for injecting fuel into the secondary combustion chamber.