"To play someone" (without a preposition) in English is rather vulgar - it means, for example, that you're in a sexual relationship with someone without real emotional interest in that person. So definitely don't say "I'm going to play him" if you're just going to play a sport with him. Say instead "tomorrow I'm going to play (ball) with him." You can also say "play against," but this generally is for a formal match, like "the Lakers will play against the Celtics tomorrow." If you're just playing a casual game, you can say "I'm going to play basketball with him" even if you're on opposite teams.

Yes, "I'm going to play him" and "I'm going to play against him" have the same meaning. Brian's answer is somewhat correct but mostly incorrect. It's true that "play someone" also means "trick someone" but a) this is relatively new slang and b) it is used this way in very different contexts than sports and games. In real life, if you said, "I'm going to play Brian in darts tomorrow," nobody would be confused or offended. (Just like you could say, "I play the piano every afternoon" and nobody would think that you trick or deceive a musical instrument... right?) There aren't any other verbs I can think of that are similar to "play him" and "play against him."

Hi,Hamid! I think that "play with X" can mean or only can mean that X is in my team. Do you agree?

I think the verb is opposite you can say Tomorrow i am going to play with him