The crystallization kinetics of Al-Gd-La-Ni metallic glasses to nanostructured phases are analyzed using differential scanning calorimetry and transmission electron microscopy. In a narrow alloy composition range near Al88Gd6La2Ni4, TEM reveals an amorphous phase separation that occurs upon annealing at low temperatures prior to crystallization. Al-enriched regions, typically 40 nm in diameter, bounded by rare-earth rich regions, are visible. Upon crystallization, α-Al forms preferentially at the interface between these phase separated regions. The relevance of this crystallization sequence to previous work in Al-RE-TM glasses and to the evolution of nanoscale microstructures common in the crystallization of other metallic glasses are discussed.