{preload_replace:preload_trick="preload_replace"}
{embed="group/template" preload='{{preload_trick}:pre_url_title="special"}'}
if called via embed you can override the preload_replace once more.
It will insert the embed-variable and parse it early.
{embed:preload}
{if segment_3==""}{preload_replace:pre_url_title="fallback"}{/if}