The original opening sequence features the X-Men demonstrating their mutant abilities to a now very distinctive instrumental theme (written by Ron Wasserman). This intro is used throughout the first four seasons. A modified version is eventually introduced in season five, episode one ("Phalanx Covenant, Part One"). In this new intro, the beginning of the theme is slightly changed. When UPN began airing repeats on Sunday mornings, an alternate credits sequence was used: a high-quality Japanese-animated version of the original opening. This modified version occasionally appears in the digital streaming release of the show, which was used for re-runs on Toon Disney.