@DeadCell
I wouldn't be surprised if that's the storyline we end up getting, but I wouldn't mind that. Sibling rivalries aren't just real in sport, they're
intense. Sae's attitude to most things leads me to believe that he doesn't really care about the social element; he doesn't even acknowledge Rin. Rin, however, definitely looks like his whole drive to be better than Sae is because he knows that'd be the only way for Sae to acknowledge him. In this example, it'd be less than a sibling rivalry and more like a one-sided obssession. If they did end up doing it, no doubt it would be a solid execution.
I'm really liking the nuance to Isagi and Rin's relationship, it's the kind of layered conflict I haven't seen in a sports manga before; really feels like the author "gets" football(or soccer). I've personally never felt more seen in a piece of sports media than this.