The Sharp-billed Canastero or Lesser Canastero (Asthenes pyrrholeuca) is a species of bird in the Furnariidae family, the ovenbirds.

The Sharp-billed Canastero is a resident breeding species in central and southern Argentina and the eastern border Andean cordillera of Chile; some birds migrate north as far as the southwest border of Paraguay, the southern border region of Bolivia, and western Uruguay, in the austral winter. Its natural habitats are subtropical or tropical dry shrubland, subtropical or tropical high-altitude shrubland, and temperate grassland.