We show that the surface of (001)-oriented La0.18Sr0.82Al0.59Ta0.41O3 (LSAT) single-crystalline substrates can be self-ordered as to become a laterally long-range ordered pattern of nanometric stripes of distinct composition. Atomically flat and periodically modulated, the resulting surface exhibits concomitant interface energy variations with an upper growing epilayer. By exploiting combined selective growth and epitaxial strain, these nanostructured substrates are used as templates to promote the self-formation of one-dimensional arrays of SrRuO3 dots.