Complex sentence: The band had thought their single "Stay in Shadow" would become a popular hit, but strong success fell on "One Thing" instead, although the track didn't find wide mainstream attention until several months after its 2003 release.
Split into simpler sentences: The band had planned on their single future "Stay in Shadow" becoming popular, but strong success fell on "One Thing" instead. Although, the track didn't find wide mainstream attention until several months after its 2003 release.