As a big football fan, yes football not soccer ;), I like the idea.
But if you focus on derbies then stick to derbies.
Real Madrid - FC Barcelona is great, but not a derby. Same for Bayern - Dortmund.
Derbies are matches between local teams.
Maybe put non derbies in a separate list on your website with a link like "not a derby, but still a great rivalty".
Maybe put non derbies in a separate list on your website with a link like "not a derby, but still a great rivalty".