The only desperate thing here is the actions of the other player. Going round supporting against you in every game, that's low and very unsporting.

It's not worth the effort to get annoyed with anyone using those tactics, but just remember his team and if you get the chance in the future to support against his team in a cup/cl match then do it. Just don't stoop to his low tactics in the current league.

Better still name and shame the team here, I for one would remember the name.