Watching Universidad César Vallejo against Universitario in the Peruvian league. Scrappy game, still 0-0 with six minutes to go, La U on top but not creating too much. But it's striking that UCV, despite playing at home, have a small ultras section but are otherwise completely outnumbered by Universitario fans. La U are one of Peru's big three, along with fellow capital clubs Alianza Lima and Sporting Cristal. But even in Trujillo, a coastal city nine hour's drive from Lima, they're a much bigger deal than the hosts.
Even the most popular club in the city, Carlos A. Mannucci*, would be outnumbered by fans of La U or Alianza (maybe not Cristal) in much the same way that Rangers and Celtic do.
Just goes to show that it's not just the likes of Scotland and Portugal with this issue, it happens all over. Happens in Mexico, too, come to think of it. My Mexican team is Cruz Azul - they're currently groundsharing at the Azteca and when I asked questions about them on the stadium tour the guy laughed and said nobody cared, and this is probably the fifth-most popular team in the country. The gap is just that big between Club América, Chivas, and everyone else.
*I once found a near-mint condition jersey of theirs from the early 2010s for $5 at a thrift store, but I neglected to properly wrap it and store it like I do my other kits, so my wife has appropriated it as a pajama top.