Abstract: In a gas turbine having a transition region between a combustor and turbine stage including a transition piece duct extending between a combustor liner and the turbine stage; an impingement sleeve surrounding the transition piece, the impingement sleeve having a plurality of apertures therein; and a compressor diffuser directing compressor discharge air into the transition region, an improvement wherein the diffuser includes a pair of outer walls flaring outwardly in a direction of compressor discharge air flow; and a pair of baffles within a flow area defined by the pair of outer diffuser walls which divide the flow area into three discrete flow passages. One passage has a substantially radial flow component; a second passage has both radial and axial flow components; and a third passage has a substantially axial flow component.